Better error logging / reporting

[bananababoo]

Currently, the only indication of resource packs not loading is an error in the console on startup.

I have a few ideas that some or all of which could be used:

1. errors.log file which generates every time a resource pack is generated if errors occur. This would just be a copy-paste of the error as it gets sent to the console.
2. A warning message in-game sent to either OP'd players/players with specific permission any time the server attempts to reload the resource pack and errors occur. This could also have the cause stated in the error.
3. A general message in game when reloading if the reload has failed (currently no output is given)