* Modified Xml::encodeJsVar() to allow it to pass through JS expressions without encoding, using a special object.
* In ResourceLoader::makeModuleResponse(), renamed $messages to $messagesBlob to make it clear that it's JSON-encoded, not an array.
* Fixed MessageBlobStore to store {} for an empty message array instead of [].
* In ResourceLoader::makeMessageSetScript(), fixed call to non-existent function mediaWiki.msg.set.
* For security, changed the calling convention of makeMessageSetScript() and makeLoaderImplementScript() to require explicit object construction of XmlJsCode() before interpreting their input as JS code.
* Documented several ResourceLoader static functions.
* In ResourceLoaderWikiModule, for readability, reduced the indenting level by flipping some if blocks and adding continue statements.
* In makeCustomLoaderScript(), allow non-numeric $version. The only caller I can find is already sending a non-numeric $version, presumably it was broken. Luckily there aren't any loader scripts in existence, I had to make one to test it.
* wfGetDb -> wfGetDB
* Added an extra line break in the startup module output, for readability.
* In ResourceLoaderStartUpModule::getModuleRegistrations(), fixed another assignment expression
* The mtime of each module is now maxed with $wgCacheEpoch before being used. I chose to make this the caller's responsibility rather than getModifiedTime()'s, otherwise custom modules can (and inevitably will) forget to respect $wgCacheEpoch
* Invalidate message blobs if they're older than $wgCacheEpoch
* Broke some long lines, converted some overly complex ternary operators to if()
* Added lots of line breaks into the output, for easier debugging.
* Added profiling for various functions.
* wfGetDb -> wfGetDB
* Fixed escaping in ResourceLoaderStartUpModule::getScript(), escape for JS rather than assuming Html::linkedScript() won't have any bad characters in it.
