0.3.1

Changes:

• When trying to find a pack file for a lang file (i.e. a file in assets/lang), use the path to the original file path first, then fall back to the modified path for backward compatibility.

This mean that if a mod tries to translate e.g. lang/sc/gui.de_DE.json into lang/sc/gui.de_AT.json, then previously, we would look for a packfile matching lang/sc/gui.de_AT.json, expecting it to contain stuff likelang/sc/gui.de_AT.json/labels/....

Now, we first look at lang/sc/gui.de_DE.json for lang/sc/gui.de_DE.json/labels/.... If lang/sc/gui.de_DE.json is not found in the map file, then use the previous scheme instead.

• Add url_prefix entry to allow translation mods to be relocatable. Every URL found in a map_file or
  even the URL of the map file itself is prefixed with url_prefix. A script can get its own URL using document.currentScript.src and could derive a url_prefix value from that.

• the 'en_LEA' test translation can now be enabled by putting 'en_LEA' somewhere in the query string.