Closes #51, Closes #167, Closes #270

Adds advanced.fileHistoryFollowsRenames setting
Adds commands to set rename following to the GitLens explorer

- Removes mix-tree support
  - Avoids nesting on the current branch
  - Caches basename
  - Replaces folder icons with theme icons
    - Folder icons will now follow the file icon theme used
  - Fixes minor nitpicks

Add folder icon
Implement branch folder
Implement branches.layout config option
Fix branch node ordering in Tree layout
Sort branch folder containing current branch correctly
- Add current getter method to BranchNode
- Implment a recursive findCurrent method on BranchFolderNode
Do not parse invalid branch name as branch folder
Expand current branch folder

Updates dependencies

Adds showWhatsNewAfterUpgrades setting
Removes messages.suppressUpdateNotice
Removes messages.suppressWelcomeNotice

Adds debug outputLevel

Adds settings for GitLens Results view
Adds layout settings for explorers
Adds not equals support
Updates README (wip)

Moves settings images into a settings folder
Adds hover setting images
Updates dependencies

Updates dependencies

Adds repository creation detection when there are no repositories

Adds a static "container"
Adds a document tracker - replaces the context tracker
Adds a line tracker
Refactors all the things - better performance, lower overhead, less code, more separation of concerns, more maintainable (hopefully)
Changes dirty blame to only happen after a "idle" delay
Closes open file annotations on edit (too expensive to track changes)