[d mode] Remove executable flag from mode files

Closes #1830
[real-world uses] Add nodeMirror
solarized selection should match gutter
[css mode] Recognize numbers with leading dot

Closes #1833
Closes #1834
Ensure scrollbar/width instability doesn't cause infinite loop

Issue #1787
Don't add null changes to history

Issue #1836
[test suite] Fix windows/IE incompatibilities

Closes #1826
Mark release 3.17
Bump version number post-3.17
Fix bug in gutter/linenumber syncing
Add checking of global variable access to linter
Mark release 3.18
Bump version number post-3.18
Note 3.18 in releases.html
Remove unused file
Make shift-delete/shift-backspace behavior match non-shift behavior

Closes #1839
Don't bind shift-delete, only shift-backspace

See 6c62022d44b3660ad75204943393bd6ea78bb228
[hardwrap addon] Add
[hardwrap addon] Fix bugginess when wrapping multiple paragraphs
[real-world uses] Add Codio