Make configure/make/make install work with spaces.

[devinamatthews]

Details:

• Having a space in the source directory, build directory, or install directory leads to major problems, both due to insufficient quoting in several bash scripts, but also due to fundamental limitations in GNU make.
• Quoting problems in scripts have been fixed.
• For the Makefile, no true solution is possible. Instead, symlink the source directory (DIST_PATH) as .dist_path and install directories (e.q. INSTALL_LIBDIR as .install_libdir). New helper rules ensure these symlinks as well as the underlying directories exist when needed.