Lua: Core improvements

The goal here is to make FF's Lua environment more robust while maintaining backwards compatibility.

The most important stuff so far (from a commit message):
* Backport a lot of the changes to the script manager made in the 2013 port
  * Make Lua's 'print' function redirect to the console
  * Add lua_dostring server command that will attempt to run the given string in the global Lua environment
  * Expose all safe default Lua library functions (newly exposed packages: package, debug, os)
  * Make Lua's 'require' look in ModDir/maps/includes, ModDir/maps/ and ModDir/ when resolving modules
* Remove unused CRC32 script validation system
* Standardize Lua console messages/warnings 
I'm guessing this code is ported from somewhere but it could benefit from a little cleanup:
- Indentation is off 
- "n" and "i" variables could be named better
- One-line "if" statements could be broken onto two lines and space out the expressions

Again, not a big deal though