Various updates to cmake support

(1) Make building OSGEOG4W optional via BUILD_OSGEO4W flag.

(2) Try first a NO_MODULE call with all find_package calls, to find
packages with config-style cmake support first.

(3) Look for PROJ4 if GDAL is found.

(4) Look for JPEG and ZLIB if TIFF is found.

(5) Install liblas-config using install(PROGRAMS ...) command (otherwise
the permissions are wrong -- no write access by owner).

(5) Remove version number from directory where config files are written.
The presence of the version can cause an incompatible config file to be
found.

(6) Improve compatibility checking and error reporting in config version
file.

(7) Define libLAS_BINARY_DIRS (so that the dlls can be found by
fixup_bundle for packages which use libLAS).
Merge pull request #60 from cffk/cmake-fixes

Various updates to cmake support