Merge pull request #148 from dalkon/master

New Lua functions
Code cleanup
Vocation code cleanup
WildcardTree cleanup
Attempt to use Clang for Travis
Another attempt to compile with Clang
Revert some of the last changes

Travis uses g++ 4.6 which doesn't support map.emplace yet.
Use nullptr instead of NULL
Make gamemasterOutfitName static const
Remove md5 password hashing

SHA1 should be replaced too (or at least be strengthened with salt, if
that is even considered enough with SHA1 today), but with the opinions
at hand (plain, MD5 and SHA1) there was never any good reason to choose
MD5 over SHA1.

If you were using MD5, consider resetting the passwords of all your
accounts; or if you really want to continue using MD5, you'll have to
add it back in your own source code copy.
Code cleanup

Replace old for loops with C++11 range-based for loops
Remove STL container clear() calls in constructors/destructors
Fix crash in WildcardTree
Fix regression in house loading

This was causing house loading to take over 4 seconds with default map.
Average startup time with default datapack is now 1 second instead of 6
seconds.
Optimize loadHouseInfo & House class cleanup