Halt the processor if hypervisor main function returns

Instead of wasting power by looping, use WFE instruction to halt the
processor until an exception occurs.
Initial stages of start up, checking for secure mode state.

Secure mode is required to get into HYP mode. If we are booted in
non-secure mode, we will have problems.
Merge branch 'development' into startup

Conflicts:
	arch/arm/head.S
Utilise new pre-processing to use include files in asm

Asm can now use include files to keep source files tidier.
Rename printk.{c,h} to printh.{c,h}

Use better naming conventions. printh stands for print hypervisor.
Also use printh.h in head.S to simplify external symbol definitions.