Auto detect engine version

[GoogleCodeExporter]

Rather than having to specify the engine version, it should be possible to 
detect it from looking at files in the path.

When loading a file, the absolute path will look like:

.../foo/BG/DATA/...

if we look in the foo directory, there will be an executable file starting with 
the name SLES_

We can use this to detect the engine version. I have the following European 
versions:

SLES_506.72   Dark Alliance
SLES_521.87   Dark Alliance 2
SLES_530.39   Champions Return To Arms

Original issue reported on code.google.com by bigianb on 22 Oct 2012 at 6:23