Add selection count view

Part of the code is from the original package `selection-count` by
@iSheeft
Selection Count specs
Fix character count test
Add selection count view

Part of the code is from the original package `selection-count` by
@iSheeft
Selection Count specs
Fix character count test
Merge branch 'character-count' of github.com:AbeEstrada/status-bar into character-count

* 'character-count' of github.com:AbeEstrada/status-bar:
  Fix character count test
  Selection Count specs
  Add selection count view
Hide selection count in other views
Merge pull request #31 from AbeEstrada/character-count

Character count