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

*.tpl / *.twig files are Smarty / Twig templates and should be treated as HTML files.
Externalize strings from Extension Manager view item template
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
Fix regressions in the display of literals and keywords in code hints.
1. keywords should be monospace.
2. literals should be dark grey.
implement updated project panel styles
make sure hex values end on boundary
Reworked the text of getting started

Updated the text to highlight features and added in some planned Sprint
24 features.
Update 'de' locale
Merge pull request #3483 from adobe/nj/extmgr-strings

Externalize strings from Extension Manager view item template
Merge pull request #3500 from mynetx/l10n-de

Update 'de' locale
Merge pull request #3498 from remotesynth/master

Reworked the getting started guide.
Merge pull request #3495 from adobe/jasonsanjose/project-panel-squash

Implement updated project panel styles
Merge pull request #3497 from adobe/randy/issue-3476

Make sure hex values end on boundary
Merge pull request #3362 from niutech/patch-2

Added syntax highlighting for *.tpl / *.twig files
String requested by adrocknaphobia
Fix GitHub case
Merge pull request #3503 from adobe/jasonsanjose/free-on-github

String requested by adrocknaphobia
String in case we want to add a "More" link to get to the extension's
home page
Merge pull request #3504 from adobe/pflynn/ext-manager/string

String in case we want to add a "More" link in Extension Manager