.travis: Use Citras ccache for builds instead of yuzus

core/core: Replace includes with forward declarations where applicable

The follow-up to e2457418, which
replaces most of the includes in the core header with forward declarations.

This makes it so that if any of the headers the core header was
previously including change, then no one will need to rebuild the bulk
of the core, due to core.h being quite a prevalent inclusion.

This should make turnaround for changes much faster for developers.

Various fixes and improvements to rasterizer cache 2: Electric Boogaloo

- Use a single cached page map.
- Fix calculation of ending page.

* Implement BC6H_UF16 & BC6H_SF16
Require by ARMS

* correct coding style

* correct coding style part 2

core: Make the main System class use the PImpl idiom

Report correct shader size.

Add predicate comparison 14 (GreaterEqualWithNan)

core.h is kind of a massive header in terms what it includes within
itself. It includes VFS utilities, kernel headers, file_sys header,
ARM-related headers, etc. This means that changing anything in the
headers included by core.h essentially requires you to rebuild almost
all of core.

Instead, we can modify the System class to use the PImpl idiom, which
allows us to move all of those headers to the cpp file and forward
declare the bulk of the types that would otherwise be included, reducing
compile times. This change specifically only performs the PImpl portion.

Seems like this was an oversee in regards to 1fd979f5
It changed GLShader::ProgramCode to a std::vector, so sizeof is wrong.

yuzu: Show game compatibility in the game list (PR ported from Citra)

* Implement POPC

* implement invert

gl_shader_decompiler: Improve IPA for Pass mode with Position attribute.

kernel: Eliminate kernel global state

Port #3825 from Citra: "travis: share environment variables with Docker"

Shaders: Implemented IADD3

As means to pave the way for getting rid of global state within core,
This eliminates kernel global state by removing all globals. Instead
this introduces a KernelCore class which acts as a kernel instance. This
instance lives in the System class, which keeps its lifetime contained
to the lifetime of the System class.

This also forces the kernel types to actually interact with the main
kernel instance itself instead of having transient kernel state placed
all over several translation units, keeping everything together. It also
has a nice consequence of making dependencies much more explicit.

This also makes our initialization a tad bit more correct. Previously we
were creating a kernel process before the actual kernel was initialized,
which doesn't really make much sense.

The KernelCore class itself follows the PImpl idiom, which allows
keeping all the implementation details sealed away from everything else,
which forces the use of the exposed API and allows us to avoid any
unnecessary inclusions within the main kernel header.

gpu: Make memory_manager private

gl_rasterizer: Remove unused variables

hle/result: Make ResultVal's move constructor as noexcept

gl_shader_cache: Remove unused program_code vector in GetShaderAddress()

Given std::vector is a type with a non-trivial destructor, this
variable cannot be optimized away by the compiler, even if unused.
Because of that, something that was intended to be fairly lightweight,
was actually allocating 32KB and deallocating it at the end of the
function.

Makes the class interface consistent and provides accessors for
obtaining a reference to the memory manager instance.

Given we also return references, this makes our more flimsy uses of
const apparent, given const doesn't propagate through pointers in the
way one would typically expect. This makes our mutable state more
apparent in some places.

yuzu: Fix two stupid errors made in #1141