Added syntax highlighting for *.tpl / *.twig files

*.tpl / *.twig files are Smarty / Twig templates and should be treated as HTML files.
Added code to return tagName when in closing tag
A few refactorings
Fixes after first review
Fixes after second review
First pass at popover styles.
Update UI
Merge branch 'glenn/hover-preview-ui' of github.com:adobe/brackets into glenn/hover-preview-ui
Rebasing
fixed padding
Increase max image size to 200x200
define offset in constant
Merge pull request #3472 from adobe/glenn/hover-preview-ui

Update Hover Preview UI for final design
Externalize strings from Extension Manager view item template
Updated by ALF automation.
Explain whether incompatible extensions require older or newer versions of Brackets. Remove hard-coded app name references in strings.
Properly force the Extension Manager to retrieve the registry on every dialog open
add new identifier colors from Lawrence Hsu.
Fix regressions in the display of literals and keywords in code hints.
1. keywords should be monospace.
2. literals should be dark grey.
Merge pull request #3489 from adobe/alf

ALF Automation
implement updated project panel styles