cpp: internal: Define all install paths
cpp: ome-xml: Define schema paths and install all schema files
cpp: compat: Add basic module introspection

This should work on ELF and Mach-O platforms, i.e. FreeBSD,
Linux and MacOS X.  It will need making conditional and
special-casing for Windows.  This is to allow data and
module directories to be discovered at runtime so that data
files and loadable modules may be loaded.  Normally one run
cmake with a fixed prefix path in which case this is known,
but for portable builds which may have the prefix changed
we need a method for dynamically discovering this
information.
cpp: compat: Remove dummy source file

Now there is a real source file present, it's unnecessary.
cpp: compat: Document compat namespace
cmake: Portability fixes for cmake 2.8.7
cpp: compat: Document module function
cpp: compat: Document filesystem canonical optional argument
cpp: compat: Add module testing notes
Merge pull request #1427 from rleigh-dundee/cpp-paths

C++: Path handling and installation location introspection