Dyncom/VFP: Convert denormal outputs into 0 when the FTZ flag is enabled.

Kernel: Properly update port counters on session disconnection.

It is not meant to be used by anything other than CreateSessionPair.

Dyncom/VFP: Perform flush-to-zero on the second operand of vsub before sending it to vadd.

externals: Update catch to 1.9.4

Upgrade AppVeyor to Visual Studio 2017

The file does not seem to exist anymore in the VS 2017 environment.

More C++14/17 goodness!

swrasterizer: add missing tc0_w attribute processing

Services/UDS: Generate 802.11 beacon frames when a network is open.

use IPCHelper for PTM services

pica: use correct register value for shader bool_uniforms

variable value is not masked. the masked and combined register value should be used instead

pica: correct bit field length for some registers

This allows the applications to retrieve 802.11 beacon frames from nearby UDS networks.
Note that the networks are still not announced anywhere.

Reduce the associated port's connection count when a ServerSession is destroyed.

Kernel: Map special regions according to ExHeader

Previously we were letting vadd flush the value to positive 0, but there are cases where this behavior is wrong, for example,

vsub: -0 - +0 = -0
vadd: -0 + +0 = +0

Now we'll flush the value to +0 inside vsub, and then negate it.

Prepare Pica registers for Geometry Shaders

This adds the handlers for the geometry shader register writes which will call the functions from the previous commit to update registers for the GS.

The commit after this one adds GS register writes, so this moves the VS handlers into functions so they can be re-used and extended more easily.

One of the later commits will enable writing to GS regs.
It turns out that on startup, most games will write 4096 GS program words.

The current limit of 1024 would hence result in 3072 (4096 - 1024) error messages:
```
HW.GPU <Error> video_core/shader/shader.cpp:WriteProgramCode:229: Invalid GS program offset 1024
```

New constants have been introduced to represent these limits.
The swizzle data size has also been raised. This matches the given field sizes of [GPUREG_SH_OPDESCS_INDEX](https://3dbrew.org/wiki/GPU/Internal_Registers#GPUREG_SH_OPDESCS_INDEX) and [GPUREG_SH_CODETRANSFER_INDEX](https://www.3dbrew.org/wiki/GPU/Internal_Registers#GPUREG_SH_CODETRANSFER_INDEX) (12 bit = [0; 4095]).

Frontend: Prevent FileSystemWatcher from blocking UI thread

Instead of tying the QFileSystemWatcher to the GameList and updating in
the UI thread, this change moves it to the worker thread. Since it gets
deleted and recreated as part of the worker thread, this prevents it from
ever getting used from multiple threads (which is why it was originally
done on the UI thread)

ir: implement new 3ds HID via ir:rst

This replaces the hardcoded VRAM/DSP mappings with ones made based on
the ExHeader ARM11 Kernel caps list. While this has no visible effect
for most applications (since they use a standard set of mappings) it
does improve support for system modules and n3DS exclusives.

Also move address space mapping out of video_core.

This is 4MB of extra, separate memory that was added on the New 3DS.

Dyncom/VFP: Revert edf30d84 and fix the FPSCR getting invalid values.