Fix ::selection bug

No issue

Fixes a weird issue where text would overlap other text.
Merge pull request #4029 from PaulAdamDavis/fix-text-selection-bug

Fix ::selection bug
Static nanoscroller integration

References #1892

A static integration of https://github.com/jamesflorentino/nanoScrollerJS  

This is WIP with the goal of getting feedback on and deciding how we should integrate this into Ghost.
Fix editor scroll depending on cursor location

Closes #4027
Properly align word-count

no ref
- Re-adds word-count styles
Merge pull request #4035 from halfdan/word-count

Properly align word-count
Merge pull request #4034 from novaugust/iss4027

Fix editor scroll depending on cursor location
Merge pull request #4015 from PaulAdamDavis/nano-scrollbars

[WIP] Nanoscroller integration
Minor tweaks to new scrollbar appearance and animations
Implements is-helper

closes #2249
- Added context to res.locals
- Added context aware is helper
- Added unit tests