18.3.4

• Updated Mesa3D to 18.3.4.

Build environment updates

• setuptools 40.7.2 -> 40.8.0;
• cmake 3.13.3 -> 3.13.4;
• pip 19.0.1 -> 19.0.2;
• wheel 0.32.3 -> 0.33.0;
• Visual Studio 15.9.6 -> 15.9.7.

Manual build information

• Remove mention of an obsolete patch.

Build script

• Remove old gles related workarounds that are only relevant for Mesa 18.2 and older;
• Use same ABI pkg-config and load Mingw environment along with MSYS2 when using Meson build to ease logic of things;
• Add a patch to ease replication of build failure with Scons 3.0.2 and newer;
• Make Meson build behave as close as possible to upstream Appveyor script;
• Support development version of Scons;
• More robust way of checking if Scons is installed as it leaves remnants behind when uninstalled which can confuse the build script;
• Make sure Python launcher query runs only once regardless of user input;
• Miscellaneous code simplifications and cleanup.