Rewrite the CMake build scripts.

 * Generate version number using `git describe`, falls back to GLC_VER.
 * Removed hard-coded search directories from find modules.
 * Added LIBRARY_INSTALL_DIR as a synonym for MLIBDIR.
 * Removed the header installation.
 * Put quotes around strings.
 * Fixed indent inconsistency.
 * Other general formatting consistency changes.
Import optimization.h from packetstream.

Packetstream does not install optimization.h when installed as a system
library, so GLCS can't find it.
Add a .gitignore file.

This ignores version.h, cmake-generated files, built objects,
and the build/ directory from build.sh.
A couple tiny fixes.

 * CMake doesn't need to check for C++ support
 * GLC_VER was still 0.6.0, even though we're at 0.6.1 now.
Changed insances of GLC to GLCS.
Added -Wall to the default release CFLAGS.

This is in relation to the suggestion in issue #5
Merge pull request #4 from ZDBioHazard/cmake_rewrite

Cmake rewrite