Fixes #3378
Closes #3751

- Fixed race conditions
- Fixed null dereference
- Fixed out-of-bounds array access
- MinimapMapblock is now allocated and added to update queue only when enabled
- Removed dependency on LocalPlayer
- Fixed code style
- Simplified expressions and program logic
- Cleaned minimap object interfaces

Move debug streams to log.cpp|h

Move GUI-related globals to clientlauncher

Move g_settings and g_settings_path to settings.cpp|h

Move g_menuclouds to clouds.cpp|h

Move g_profiler to profiler.cpp|h

Move texture_min_size even further down the pipe. Now, textures are JIT-upscaled using an image transformation, right at the time they're added to a mesh or particle; images used in 2D elements are left unscaled. This should fix any remaining issues with HUD elements.

Directely or indirectly optimises the following functions:

* MapBlockMesh::MapBlockMesh
* MapBlockMesh::getTileInfo
* MapBlockMesh::makeFastFace
* MapBlockMesh::getSmoothLightCombined

* Increase performance (client)
* Avoid changing a global value to solve a local problem

This reverts commit d25ff8fd.

* Increase performance (client)
* Avoid changing a global value to solve a local problem

Signed-off-by: Craig Robbins <kde.psych@gmail.com>

Leads to the following increases:
getSmoothLight() approx.     40% increase
getTileInfo() approx.        25% increase
MapBlockMesh::MapBlockMesh() 25-30%

Signed-off-by: Craig Robbins <kde.psych@gmail.com>

CNodeDefManager::get()
VoxelManipulator::addArea()

getTileInfo() ~1.5x faster
getSmoothLight ~2.0x faster

- Don't create and cache an extruded mesh for every (non-node) item.
  Instead use a single one per image resolution.

- For cubic nodes reuse a single wield mesh too

- Improve lighting of the wielded item

- Increase far value of wield mesh scene camera, fixes #1770

- Also includes some minor refactorings of Camera and GenericCAO.

sky.cpp: m_bgcolor.getAlpha() was being used before initialised

mesh related: m_highlight_mesh_color was being used uninitialised

Pass light sources in blue channel of vertex color instead of decoded light for all special drawtypes.
Plus some style fixes and optimizations.

Skip shading for lightsources and top of the nodes.
Fixes liquid sources and flowing surfaces having different brightness.