version: provide a bare version-only constant

This commits add a new global constant containing only the version number,
without build date.
This is useful for tools built around MAME, which would use it to track
capability changes for compatibility layers.

Signed-off-by: Luca Bruno <lucab@debian.org>
luaengine: add emu.app_name()/app_version() methods

This commit adds two methods to LUA interface, allowing scripts to
programatically retrieve current running application name and version.
The idea is to make scripts aware of changes in the API, by
linking it to current version number. Compatibility helpers can then
be added to LUA scripts to keep working across API changes.

Signed-off-by: Luca Bruno <lucab@debian.org>
Merge pull request #70 from lucab/lucab/mame-lua/appinfo

luaengine: add API versioning [Luca Bruno]