Enable ccache usage on Travis

Common/string_util: add StringFromBuffer() function

GPU: Fixed ghosting when drawing with blending disabled

Only independent blending on render target 0 is implemented for now.

This fixes the elongated squids in Splatoon 2's boot screen.

GLCache: Align compressed texture sizes to their compression ratio, and then align that compressed size to the block height for tiled textures.

Rasterizer: Flush the written region when writing shader uniform data before copying it to the uniform buffers.

GLCache: Align compressed texture sizes to their compression ratio, and then align that compressed size to the block height for tiled textures.

This fixes issues with retrieving non-block-aligned tiled compressed textures from the cache.

Rasterizer: Flush the written region when writing shader uniform data before copying it to the uniform buffers.

This fixes the flip_viewport uniform having invalid values when drawing.

Ubuntu 18.04 already has cmake 3.10.2

Use Ninja for Travis builds

GLRenderer: Write the shader stage configuration UBO data *before* copying it to the GPU.

This should fix the bug with the vs_config UBO being uninitialized during shader execution.

convert input buffer (std::vector<u8>) to string, stripping zero chars

Service/MM: add service and stub some functions

gl_shader_decompiler: Implement BFE_IMM instruction.

GLCache: Fixed copying compressed textures in the rasterizer cache.

This avoids the problem of only copying a tiny piece of the textures when they are compressed.

We now use glCopyImageSubData, this should avoid errors with trying to attach a compressed texture as a framebuffer's color attachment and then blitting to it.

Maybe in the future we can change this to glCopyTextureSubImage which only requires GL_ARB_direct_state_access.

gl_shader_decompiler: F2F: Implement rounding modes.

Service/nfp:user : stub some functions.

gl_shader_decompiler: Additional decodings, remove unused stuff from TEX

GPU: Support changing the texture swizzles for Maxwell textures.

gl_shader_decompiler: Implement ISETP_IMM instruction.

GPU: Implement sampling multiple textures in the generated glsl shaders.

 gl_shader_decompiler: Implement LD_C instruction.

All tested games that use a single texture show no regression.

Only Texture2D textures are supported right now, each shader gets its own "tex_fs/vs/gs" sampler array to maintain independent textures between shader stages, the textures themselves are reused if possible.