HID: reset acceleroeter and gyroscope index in Init

Updated Citra forum link

The Citra forum (discuss.citra-emu.org) has recently been down. The link that has been added 
in this file now leads to an error pages. I update updated the link so it now leads to Citra's new
forum.

loader: Add support for 3DSX special relocation types

As per devkitPro/3dstools@47bea18

HID: manages updating itself using correct ticks

GSP::WriteHWRegsWithMask: fix register mask

SDL2: Config, fix double to float warning

Qt: Fix UI related warnings and bonus ui file format 

Implement some TODOs in the code.

Service/AC: add ac:i service

Threads: Check the process' resource limit for the max allowed priority when creating a thread and remove the priority clamping code.

Thread: Added priority range checking to svcSetThreadPriority and removed priority clamping code from Thread::SetPriority.

 Kernel: Implemented Pulse event and timers.

Prevents appveyor from attempting to deploy except on the nightly repo

config: Add option for specifying screen resolution scale factor.

Emulate motion sensor in frontend

Don't yield execution in SleepThread(0) if there are no available threads to run

Kernel/Semaphore: Fixed a regression in semaphore waits.

Closes #2400

Kernel: Removed the priority boost code for starved threads.

Kernel: Don't attempt to yield execution in SleepThread(0) if there are no available threads to run.

With this we avoid an useless temporary deschedule of the current thread.

Kernel: Remove some unused functions.

After hwtesting and reverse engineering the kernel, it was found that the CTROS scheduler performs no priority boosting for threads like this, although some other forms of scheduling priority-starved threads might take place.

For example, it was found that hardware interrupts might cause low-priority threads to run if the CPU is preempted in the middle of an SVC handler that deschedules the current (high priority) thread before scheduling it again.

Closes #1904

The regression was caused by a missing check in #2260.

The new behavior is consistent with the real kernel.

Kernel: Mutex priority inheritance and synchronization improvements.