Handle tolua++ being unmaintained

[Erik Ogenvik]

Tolua++ is effectively unmaintained, and is incompatible with newer versions of Lua.
This makes building Ember more and more harder for each year.

A solution must be found, and it must be coordinated with CEGUI which also uses tolua++.

Some possible solutions:
* keep on going, perhaps it's not as bad, perhaps distros will keep on packing lua 5.1 for some while?
* keep it as it is and make sure Hammer installs Lua 5.1
* find a replacement

[Todd Carnes (toddcarnes)]

According to this bug report...

https://bitbucket.org/cegui/cegui/issues/776/add-support-for-lua-52

... it seems that CEGUI should support Lua versions 5.2 and higher now.

[Todd Carnes (toddcarnes)]

Also found this fix in the Arch Linux AUR repo that updates tolua++ for Lua 5.3

https://aur.archlinux.org/packages/tolua%2B%2B_5.3/