Fixed a 'malformed assignment' issue, read more

I've also added some support for compiler errors in general, but these
will get expanded on later.

I've also quickly added a valgrind option to the tests and found a few
leaks. I'll deal with these later.

Summary of changes:

* Clarified the lifetime of the bytecode in memory
* Erroneous routines exit without compiling
* Empty VMs don't run
* Added a check for malformed assignments
* Renamed "routine" to "module" within the VM
* VM no longer tries to free the bytecode - must be done manually
* Started experimenting with valgrind, not yet ready

source/toy_bytecode.h

@@ -7,6 +7,8 @@ typedef struct Toy_Bytecode {
 	unsigned char* ptr;
 	unsigned int capacity;
 	unsigned int count;
+
+	unsigned int moduleCount;
 } Toy_Bytecode;
 
 TOY_API Toy_Bytecode Toy_compileBytecode(Toy_Ast* ast);