All calling code assumes that the rasterizer will be in a valid state,
which is a totally fine assumption. The only way the rasterizer wouldn't
be is if initialization is done incorrectly or fails, which is checked
against in System::Init().

We move the initialization of the renderer to the core class, while
keeping the creation of it and any other specifics in video_core. This
way we can ensure that the renderer is initialized and doesn't give
unfettered access to the renderer. This also makes dependencies on types
more explicit.

For example, the GPU class doesn't need to depend on the
existence of a renderer, it only needs to care about whether or not it
has a rasterizer, but since it was accessing the global variable, it was
also making the renderer a part of its dependency chain. By adjusting
the interface, we can get rid of this dependency.

video_core: Remove unimplemented Start() function prototype

memory: Remove unused GetSpecialHandlers() function

 kernel/process: Use accessors instead of class members for referencing segment array

kernel/thread: Fix potential crashes introduced in 26de4bb5

This amends cases where crashes can occur that were missed due to the
odd way the previous code was set up (using 3DS memory regions that
don't exist).

gl_shader_decompiler: Remove unused variable in GenerateDeclarations()

Using member variables for referencing the segments array increases the
size of the class in memory for little benefit. The same behavior can be
achieved through the use of accessors that just return the relevant
segment.

This is just unused code, so we may as well get rid of it.

core/memory: Get rid of 3DS leftovers

gl_shader_manager: Make ProgramManager's GetCurrentProgramStage() a const member function

Given this has no definition, we can just remove it entirely.

This variable was being incremented, but we were never actually using
it.

This function doesn't modify class state, so it can be made const.

Removes leftover code from citra that isn't needed.

Added ability to change username & language code in the settings ui. Added IProfile::Get and SET::GetLanguageCode for libnx tests (#851)

 sink_details: std::move std::function instances 

service: Add migration services

math_util: Always initialize members of Rectangle

video_core: Make global EmuWindow instance part of the base renderer …

kernel: Move object class to its own source files

kernel/thread: Minor changes

input_common: minor changes

yuzu: Use Qt 5 signal/slots where applicable

kernel/vm_manager: Minor changes

vfs_vector: Minor changes

gl_shader_manager: Take ShaderSetup instances by const reference in UseProgrammableVertexShader() and UseProgrammableFragmentShader()

Makes the signal/slot connections type-safe instead of string-based.

Avoids unnecessary atomic reference count increments and decrements

hw: Remove unused files

gl_state: Make texture_units a std::array

service/ns: Add missing ns services

service: Add the psc services

Makes our immutable state explicit.

These two variables correspond to address ranges.