Avoid Lua stack overflow when picking lots of props

According to the Lua manual, "you are responsible for controlling
stack overflow", especially when pushing elements onto the stack in
a loop (see http://www.lua.org/manual/5.1/manual.html#3.2).

Pushing too many elements onto the stack does not crash immediately,
but will corrupt the heap, potentially causing random crashes later.

MOAIPartitionResultBuffer::PushProps() pushes props onto the stack
in a loop, so it must make sure that the stack is big enough to
accomodate them by calling lua_checkstack().
Avoid Lua stack overflow in MOAIPathTerrainDeck:getTerrainVec()

See previous commit for details.
Avoid Lua stack overflow in MOAITouchSensor:getActiveTouches()

See previous commits for details.
Merge pull request #733 from theGoodEvil/lua_stack_overflows

Avoid (some) Lua stack overflows