- 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