Add script source to GM_info
Pass all required arguments (and only those) to the InstallListeners.
Add a comment describing the side effects of RemoteScript#install.
Fix cleanup of the downloaded files when cancelling an installation.

ScriptInstall#cancel already calls this._remoteScript.cleanup, but
this._remoteScript wasn't properly set before.
Ensure the new tab is opened in the current chrome window.

Since the tab (and thus the content window) may have been moved to a
different chrome window since the script was injected, we can't cache
the chrome window for the purpose of figuring out where to place the
new tab.

Fixes #1758.
Don't unnecessarily pass the chrome window to GM_registerMenuCommand.
Merge remote-tracking branch 'ventero/addonfixes'

Fixes #1757
Merge remote-tracking branch 'aidanhs/GM_info-script-src'

Fixes #1738