* implement the "lanes" feature, similar to the description in #1986. 

* implement the "snaps" feature, similar to the description in #1985. 

* disconnect the hash calculation of a Version object from its path, it helps to be flexible with schema changes and avoid HashMismatch exceptions

* snap and tag are working in conjunction

* snap - have head snap as Ref in memory

* fix modified status after snap

* change parent hash prop if version hash is changed

* change parent prop to be an array of parents

* fix snap head upon untag

* fix untag for snaps

* provide a more descriptive error message when a hash is missing

* avoid fetching all versions when not needed

* fix bug of second tag after snap

* fix bit-log to show snaps. support diverged snaps history. fix import and export of snaps. write remote head to a new file at refs/remote

* implement import --object when the local head is different than the remote head

* (wip) started working on bit lane command

* revert the implementation of saving different "Component" objects per lanes (done by dd20bb1)

* implement Lane object (inherit BitObject)

* add basic validation for "lane" object, introduce "bit cat-lane" command, fix "bit status" when snapping on master then on a new lane

*  remove scope-name from lane-id

* fix bit diff to work with snaps

* bit checkout is working for Snaps

* add tests for bit merge with snaps

* recognize diverged components, suggest to merge them in bit status and throw error on bit import in case --merge was not entered

* fix status of merge-pending to show the number of snaps existing on local/remote

* add the common snap before diverge data into the diverge results

* implement a snap-merge of diverged components

* fix bit-status to show an unresolved component as such, implement bit merge --resolve

* implement merge --abort

* prevent tag/snap/checkout/merge a component with conflicts, enable untag/remove

* basic lane export is working

* write exported components heads into refs/remote

* started implementing "bit import" lanes

* move current-local-name from .bitmap to scope.json

* basic functionality of switching between master to a lane is working

* add test for "bit diff" when on a lane, fix "bit status" when snapped on a lane, refactor "diverge" data

* Started working on "bit merge" for lanes. fix tag & checkout lane for multiple components

* fix tests, fix exporting from master to write the snaps into the remote ref

* basic "bit merge" of lanes is working

* fix merging from a remote lane into master

* start working on noSnap flag

* consolidating merge-lanes with snap-merge logic. add merge-snaps output

* implement --no-snap and --message flags of bit-merge

* add existingOnWorkspaceOnly flag for bit-merge

* add e2e-test and output when using --existing flag for bit-merge

* implement bit lane --merge and --not-merged flags

* add a flag "new-lane-name" for bit-checkout

* introduce new flags for "bit import": --new-lane-name and --checkout

* copy components data from origin lane to a newly created lane (except master)

* introduce "bit switch" to switch/create/import lanes

* introduce "bit fetch" command to fetch remote objects

* improve lane-id

* bit fetch is working, change tests to work with bit-switch and bit-fetch

* basic case of switching from a lane back to master is working

* basic case of importing a component when checked out to a lane

* change bit-lane to function only as list/show not as "add". change the output according to the new specs

* started working on workspace-lanes

* implement workspace-lane object to save the current (checked out) versions per local lane

* export with no ids when checked out to a lane, exports the lane

* change the export output to indicate that lanes were exported

* separate getAllBitIds and getAllIdsAvailableOnLane methods to not use the same cache

* implement remove local lanes

* enable fetching lane list from a remote

* when user is checked out to a lane, "bit remove" removes the component from the lane only

* enable removing remote lanes

* block tagging when on a lane for now. we might change it later

* implement auto-snap

* skip a test about fetching dependencies parents for now, it will be back once the backward compatibility is implemented

* implement auto-snap on lanes

* fix ModelComponent.latest() to always work with the current lane

* skip an e2e-test for now until backward compatibility is implemented

* support feature-toggle mechanism

* backward compatibility: do not save snaps.head and component parents when lane feature is disabled

* backward compatibility - fix import from old clients

* throw errors when trying to use lanes/snaps and the feature is disabled

* re-enable some tests now that backward compatibility is supported

* extract create-lane functionality to a new file

* extract export-lanes functionality to a new file

* refactoring. make sure fetch api gets bit-ids or remote-lane-ids. (remove the hack of converting lane-id into bit-id)

* clean some unneeded flags on checkout command

* fix MergeConflictOnRemote to be backward compatible

* refactoring and mark lane flags as experimental

* remove some dups snap/tag

* extract switch lane logic from checkout-version.ts to switch-lanes.ts

* consolidate snap-model-component into tag-model-component

* clear confusion between remoteHead and laneHeadRemote

* extract merge-lanes code to a new file merge-lanes.ts, refactor RemoteLane to use RemoteLaneId whenever possible

* extract the diverge-data into a new file, add a new prop "remoteHead" and avoid adding the master remote into laneRemoteHead

* extract the logic of version traversal into a new file

* remove the hack of reseting the model-component heads

* fix some forward compatibility issues with index.json

* fix RemoteLaneId to indicate that a scope is mandatory

* change ModelComponent.snaps.head to ModelComponent.head

* fix bug when merging components to master

* change variables with snapHead to head