This was used to name snapshot releases of the Network2 branch, and has
seen almost no use since.
C4ENGINEINFO(LONG) was a duplicate of C4ENGINENAME and C4ENGINECAPTION.
There's no reason to have CMake assemble a version string, then have a
similar (but slightly different) string built by the C preprocessor.
Since CMake already has the values we want, just dump those into the
macros.
In order to get an embedded build ID, add a new CMake cache variable
named OC_BUILD_ID. This variable can contain an arbitrary string, but
it is suggested that you use a hierarchical string starting with your
DNS domain, reversed, as in "com.example.openclonk.arbitrarystring"
(think java packages).
This assumes that pre-release versions will always have a x.y.90 version (or
higher), and will in those cases display the revision in place of the fourth
version segment.
Removed unused C4SHORTVERSION and C4EDITORCAPTION, replaced unset C4XVERBUILD
with C4XVER4, and more clearly separated the configuration from the derived
values.