archive_backend: Remove unnecessary const from return types

This doesn't return by reference so const isn't really necessary

hwrasterizer: Use depth offset

DisassembleMemHalf: actually use width in determining opcode name

command_processor: Get rid of variable shadowing

HLE/SVC: Implement UnmapMemoryBlock.

This implementation will need to be (almost completely) changed when we implement multiprocess support.

Add optional GL_KHR_debug support

Not much thought went into that one...

HLE/Sockets: Fixed the buffer offset in recvfrom.

Update appveyor.yml to use VS2015 CMake generator

Gamelist: supply default settings for QSettings config

services: Update some function tables

arm_dyncom_dec: Fix decoding of VMLS

Previously, all VMLS variants would misdecode as CDP
(which isn't necessarily wrong in itself, however
VMLS has it's own label of execution)

video_core: Make the renderer global a unique_ptr

HLE/Timers: Reset OneShot timers when they are acquired instead of when they're triggered

core: Use unique_ptr for holding the interpreter instances

Closes #1139

swrasterizer: Add missing override specifier

SVC: Fixed ArbitrateAddress to behave as it does on hardware.

dyncom: Handle modifying the APSR via an MRC instruction

This was verified with hwtests that i plan to upload later on.

svc: Remove superfluous printf argument

Add a return value in ForeachDirectoryEntry 

Closes #1277