Request option & other fixes

• Added a --request option to allow users to supply requests that would normally go in rc.glsl through the command line.
• Fixed a memory leak that occurred when the GLava window was repositioned (or the root pixmap updated) while "xroot" was selected.
• Fixed a bug where preprocessor directives would not work at the end of the file, due to not having a trailing line break.
• Most compilation output has been now limited to the --verbose option.