Add new packages and build scripts for various libraries

- Added Nuklear GUI library with build script and configuration.
- Introduced OpenH264 encoder/decoder with build configuration.
- Added PortAudio library for audio I/O with custom build script.
- Included Python Execnet for multi-Python deployment.
- Added Pytest Xdist plugin for distributed testing.
- Introduced Shaderc for shader compilation tools.
- Added Snappy compression library with necessary patches and configuration.
- Included SoundTouch audio processing library with build configuration.
- Added SRT library for secure reliable transport.
- Introduced VapourSynth video processing framework with configuration.
- Added Vid.stab for video stabilization.
- Included WebRTC Audio Processing library with build configuration.
- Added X264 video encoding library with patches for POSIX compliance.
- Introduced X265 video encoder with build configuration.
- Added XKeyboard Config for X keyboard configuration files.
- Included Xorg XKBComp for keyboard description compilation.
- Added Xvidcore MPEG-4 video codec library with configuration.
- Introduced ZeroMQ messaging system with patches and build configuration.
- Added Zimg library for scaling and colorspace conversion.

extra/x265/x265.toml

@@ -0,0 +1,33 @@
+[build]
+type = "cmake"
+
+[build.flags]
+build_dir = "build"
+configure = [
+    "-G Ninja",
+    "-W no-dev",
+]
+source_subdir = "source"
+
+[dependencies]
+build = [
+    "cmake",
+    "ninja",
+    "nasm",
+]
+runtime = [
+    "libcxx",
+    "libunwind",
+]
+
+[package]
+description = "Open Source H265/HEVC video encoder"
+homepage = "https://bitbucket.org/multicoreware/x265_git"
+license = "GPL-2.0-or-later"
+name = "x265"
+version = "4.1"
+
+[[source]]
+extract_dir = "$name-$version"
+url = "https://bitbucket.org/multicoreware/x265_git#$version"
+cherry_pick = [ "b354c009a60bcd6d7fc04014e200a1ee9c45c167", "51ae8e922bcc4586ad4710812072289af91492a8", "78e5ac35c13c5cbccc5933083edceb0d3eaeaa21" ]