Fix missing semicolons
asm: Add "emit" macro

The emit macro allows you to write assembly code with asm in a convenient
manner, for example (snippet from asm-test.pwn):

	emit proc      1;
	emit push_s    12;
	emit push_c    4;
	emit sysreq_d  GetNativeAddressFromName("print");
	emit stack     8;
	emit retn      ;

In order for this to work there must be defined a variable "ctx" of type
AsmContext that holds the current emit context.