Lua: Expose player functions GetFortPoints, GetFrags, GetDeaths
Lua: Fix execution errors not being caught and failing silently
 * Backported from fortressforever/fortressforever-2013@c4061fb5f70c8ff2825d8faa973d440cb90e7e79
Lua: Add global function GetGameDescription
Lua: Add buildable_killed(buildable, damageinfo) callback
Lua: Add player:SetDisguise(int teamId, int classId, bool isInstant)
Lua: Allow IncludeScript to use paths to subdirectories
Lua: Add player:IsInAir(unitsAboveGround) overload
 * checks if the player is the specified number of units above the ground
Lua: Add player:IsFlashlightOn()
Lua: Fix AT.kForceThrowItems and AT.kForceDropItems not doing what they say
 * AT.kForceThrowItems will simulate the player hitting the throw flag key
 * AT.kForceDropItems will simulate the player respawning, and therefore will force all their items to drop (info_ff_script:onownerforcerespawn() will be called)
Fix compile errors
Lua: Remove arbitrary restriction on loading script files after the initial load sequence
 * This disallows IncludeScript from being called after the map Lua is first loaded, which in turn disallows conditionally/lazy-loaded scripts for no apparent reason
Lua: Make player:IsFlashlightOn return a boolean
Lua: Fix player:SetDisguise trying to set the disguise of non-spy classes
Lua: Expose player:ResetDisguise
Lua: Add player:AddHealth(healAmount, allowOverheal) overload
Lua: Fix AT.kForceDropItems causing the flag to return instantly
 * Use onownerdie instead of onownerforcerespawn
Lua: Rename DisplayMessage to SendHintToPlayer and add SendHintToTeam/SendHintToAll functions
 * DisplayMessage still exists for backwards-compatibility
Review: Better IsFlashlightOn comment
Merge pull request #62 from fortressforever/features/lua-enhancements

Lua: Various improvements