Fix undefined variable access.
Merge pull request #1698 from Ventero/pr-1698

Fix undefined variable access.
Install .user.js files dropped into the Add-ons Manager.

Refs #1663
Call default onDrop() only when there are non-user-scripts.

Fixes #1663
Make Scratchpad the default user script editor.

See: https://developer.mozilla.org/en-US/docs/Tools/Scratchpad

Fixes #1688
Show parse-time script errors when installing.
Localize string in install dialog.

Refs #1695
Localize strings in parseScript module.

Refs #1695
Localize strings in script module.

Refs #1695
Localize various orphaned strings.

Fixes #1695
Fix typo causing unnecessary array duplication
Merge pull request #1700 from Lekensteyn/fix-typo

Fix typo causing unnecessary array duplication
Added websites submenu to monkey menu.

Cherry picked from 21ba70d3c2b6ed363b70d968dc07b99c3446a02f +
967d4f89243b45e9b4957ed32bbfed629c631906

Fixes #1684
Fix incorrect string name.
Refactor xmlhttprequester into a JS module.

Also refactor apiLeakCheck, to support that change.
Remove obsolete mac-specific toolbar graphics.

See 99341d5af0e008a8ce24d5b1fae28e3ac254c18e
Add a 'redirectionLimit' option to GM_xmlhttpRequest.

Fixes #1690
Fail predictably when trying to read the contents of a non-file.
Download dependencies of scripts installed from the clipboard.

Fixes #1699.
Localize install-from-clipboard download error message.