exo2: Implement uncompressor stub and boot code up to Main().

exo2: implement some more init (uart/gic)

exo2: implement more of init

exo2: improve reg api, add keyslot flag setters

exo2: implement se aes decryption/enc

exo2: fix bugs in loader stub/mmu mappings

exo2: start skeletoning bootconfig/global context types

arch: fix makefile flags

exo2: implement through master key derivation

exo2: implement device master keygen

exo2: more init through start of SetupSocSecurity

exo2: implement pmc secure scratch management

se: implement sticky bit validation

libexosphere: fix building for arm32

libexo: fix makefile flags

libexo: support building for arm64/arm

sc7fw: skeleton binary

sc7fw: skeleton a little more

sc7fw: implement all non-dram functionality

exo2: fix DivideUp error

sc7fw: implement more dram code, fix reg library errors

sc7fw: complete sc7fw impl.

exo2: skeleton the rest of SetupSocSecurity

exo2: implement fiq interrupt handler

exo2: implement all exception handlers

exo2: skeleton the entire smc api, implement the svc invoker

exo2: implement rest of SetupSocSecurity

exo2: correct slave security errors

exo2: fix register definition

exo2: minor fixes

This was tested using `https://github.com/node-dot-cpp/alloc-test` plus a few other by-hand tests.

It seems to work for the case we care about (sysmodules without thread cache-ing).

External users are advised to build with assertions on and contact SciresM if you find issues.

This is a lot of code to have gotten right in one go, and it was written mostly after midnight while sick, so there are probably un-noticed issues.