Add matrix skeleton file; updated makefile.

Add:
	src/matrix.c
		-file to contain functions for point matrix creation and manipulation.
		-add headers for functions to createMatrix(), expandMatrix(),
		addPoint(), etc.

	src/matrix.h
		-define and typedef the Matrix_t struct.

	makefile
		-add target to compile matrix.c into executable.
Popualate and test matrix functions.

Add:
	src/matrix.c
		-populate and test matrix functions.
		-run tests through valgrind memcheck to ensure pristine memory.

	src/engine.c
		-add testMatrix(), to test a variety of matrix functions

	makefile
		-modify gcc FLAGS variable: replace -Ofast with -O0 to minimize
		optimizations and add -g flag, allowing valgrind to better identify
		culprit code (with line numbers and leak traces).
Add some documentation, function header comments.

Add:
	src/(engine, matrix, utils).c
		-add documentation comments at the head of each file, briefly explaining
		its general purpose and enclosed functions.
		-add comments before every function header, describing the function's
		role.
Add content to README, install.sh.

Add:
	README.md
		-add content to README: list dependencies, provide installation,
		compilation, execution, and cleanup instructions.

	install.sh
		-add shell-script to install any project dependencies (currently the SDL
		library).

	makefile
		-change flag to link SDL library from "-lSDL" to the output of
		"sdl-config --libs"