Add transformation headers, addTransformPt.

Add:
	src/matrix.c
		-add addTransformPoint(), a quasi-overloaded addPoint(), which allows a
		specific w variable to be added as opposed to the default 1. Used in
		creating transformation matrices, whereas addPoint() will be used only
		to add coordinate points.

	src/matrix.h
		-add function headers for all necessary transformation functions.

	makefile
		-add -Wunreachable-code error flag.
Add matrix multiplication, diff matrix printing.

Add:
	src/matrix.c
		-add multiplyScalar() and multiplyMatrix(), which handle the
		multiplication of a matrix by both scalar values and other matrices.
		-add helper-function dotProduct(), which returns the dot products of two
		2D arrays at a given row and column.

	src/matrix.c
		-move printMatrix() to printPointMatrix(), which prints a Matrix_t with
		(x, y, z, w) formatting
		-add printMatrix(), which prints a matrix in matrix format.
Add three matrix-creation functions.

Add:
	src/matrix.c
		-add createIdentity(), createTranslation(), and createScale(), which
		create and return identity, translation, and scaling matrices
		respectively.

	src/engine.c
		-add calls to test transformation matrices.
Add rotation, screen conditional. Fix translation.

Add:
	src/matrix.c
		-add createRotation(), which creates and returns a matrix for rotation
		about a given axis and argument

	src/matrix.h
		-add macros for each axis, currently only used in calls to
		createRotation().

	src/screen.c
		-add conditional to drawPixel() that exits the function if either the x
		or y argument is outside of the screen boundaries.

Fix:
	src/matrix.c
		-createTranslation(), in updating the last column of the 4x4 translation
		matrix with dx, dy, and dz values, was only updating the first row
		because the row values weren't changed per line after the original line
		was copy-and-pasted three times.