If the option USE_VERSIONED_DIR is set to ON (default is OFF), then
most files are installed in a ${suite}-${label}/ subdirectory
(e.g. header files go in "/usr/include/opm-2013.03/"). This enables
us to easily install backports of newer versions on systems which
have a system package for an older one, without getting conflicts.
By using a separate variable for this we can easily grep for where
the build system depends on its own location, and also change the
policy regarding this later.
Note that there is no opm-macros module; this is a "psuedo"-module
which links to an additional one (currently, the one we're in)
Options are boolean flags that are stored... in the cache, whereas
cache variables are also stored in the cache, but can have a variety
of types (including booleans). It was possible to confuse the two,
because if you set it as a variable on the command line, it will
override both.
Most of the file is not changed from some sensible default anyway, so we
can store this in the template directory and have a much more manageable
local file which just contains the relevant changes.