Unit tests for block comment, line comment on empty lines, line comment
auto-switching to block comment & vice versa, and commenting in mixed
syntax modes.

The commented-out tests don't pass yet.
Merge remote-tracking branch 'origin/master' into pflynn/block-comment-unittests

* origin/master: (154 commits)
  Made ContextMenu actually call its superclass constructor (instead of assigning a new menu to this.menu, which isn't actually used).
  Increase test timeout when requesting a native file system for a drive.
  Code review: add testcase for nonempty invalid regex; remove unneeded JS dependency.
  Align equals signs
  Code review cleanups
  Code review cleanups
  rename back to copyPath()
  fix jslint errors
  code review comments
  more code review comments
  Small jsdoc fix in _fsErrorToDOMErrorName
  For #2310, consider an empty line number query valid, but show error if the line number is out of range of the editor
  code review comments
  Use scrollTop instead of scrollIntoView for #2130
  Add a few more unit tests for Find. Update unit-test harness files to include this suite.
  Rename _nativeToFileError to _fsErrorToDOMErrorName
  Increase timeout when waiting for a new NativeFileSystem to be created.
  Global FileError.* and error.code refactor
  External NativeFileError
  Fix jsdocs and change _nativeToFileError signature
  ...
Merge remote-tracking branch 'origin/master' into pflynn/block-comment-unittests

* origin/master:
  Forgot to fix up other callers to functions with changed signature
Update block-comment unit tests to account for pull reqs #2121 (handle line
comments differently), #2133 (single-line block comment mode when Line
Comment invoked in CSS/HTML/etc. - enable test coverage), and #2148 (don't
replace whole selection - which means tests must work around #2335).
Add more tests & change expected behaviors per #2337 and pull #2342.
Clarify comments now that code's expected behavior follows simpler rules.
More block-comment unit tests: cases where selection extends outside bounds
of multi-line comments (per NJ); cases where selection edges are in
whitespace (tricky cases in current implementation since token info is
ambiguous); case with two immediately adjacent block comments.
Adds sass support

This commit requires that codemirror be updated to include sass first.
I have already submitted this change
Add support for opening files at startup.
Update Getting started screenshot for 'de' locale, transparent background
Translated strings for sprint 20
Use master branch on build status badge
Merge pull request #2362 from adobe/pflynn/block-comment-unittests

Unit tests for Toggle Block Comment
There is no need to extend the replaced text when adding a :
Merge pull request #2653 from adobe/glenn/file-association

Add support for opening files at startup.
Merge pull request #2884 from TomMalbran/tom/fix-issue-2875

Fix Issue #2875: CSS code hints overwrite 1 char too many on current line
Merge pull request #2609 from bryanstedman/master

Adds sass support.
Merge pull request #2840 from mynetx/l10n-de

Update Getting started screenshot for 'de' locale, transparent background
Merge pull request #2871 from jbalsas/spanish-translation-sprint-20

Spanish strings for sprint 20
Disable two unit tests due to marijnh/CodeMirror#1255. Bug already filed
to track re-enabling them.
Merge pull request #2890 from adobe/pflynn/disable-failing-tests

Disable two unit tests that are failing intermittently due to CM bug