PSD article7:  implementation and tests of Vehicle class in C

New/Changed Files:

vehicle.h:	class definition of Vehicle class in C

vehicle.c:	class implementation of Vehicle class in C

simpletestvehicle.c: test program that moves a vehicle around

Rest of files unchanged from previous tarball:

vv.[ch]: a new "subclass of vector2" that overrides the print method
         to print more info - essentially overrideprint.c reimplemented
	 as a proper subclass

simpletestvv.c: simple tests for vvs and vector2s, print the answers

testvv.c:	unit tests for vvs and vectors, answers encoded, only
                complains about failures

overrideprint.c: an example which modifies an object's print() method on the fly

vector2.[ch]:	module implementing Vector2 class in C

testsupport.h:	unit testing support - prototypes and macros

testsupport.c:	unit testing support - functions

simpletestvector2.c: simple tests for vectors, print the answers

testvector2.c:	unit tests for vectors, answers encoded, only complains about failures
