Block any (Xray/XPC) wrapped arguments in apiLeakCheck().

Refs #1494
Add missing semicolons.
Strip UTF-8 BOM(s) from the front of the user script.

Fixes #1823
Remove ScriptChannel.

Using the resource URL of a resource with a name that ends with
.user.js would lead to surprising results: GM_getResourceText
would return the actual resource content, but using the URL returned
by GM_getResourceURL would result in the parent script content being
returned.

Refs 1999be3484154d22f41afba465fb56366e6cf61b.
Remove FF3 specific code path.
Added cues for text editors to set themselves up properly.
Bring all text files in line with project whitespace rules.