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/devil/devil.toml

@@ -0,0 +1,31 @@
+[build]
+type = "cmake"
+
+[build.flags]
+build_dir = "build"
+source_subdir = "DevIL" 
+configure = [ "-DCMAKE_POLICY_VERSION_MINIMUM=3.5", "-DCMAKE_CXX_STANDARD=14" ]
+
+[dependencies]
+build = ["cmake"]
+runtime = [
+    "libpng",
+    "jasper",
+    "lcms2",
+    "libjpeg-turbo",
+]
+
+[package]
+description = "Library for reading several different image formats"
+homepage = "https://sourceforge.net/projects/openil/"
+license = "LGPL-2.1-or-Later"
+name = "devil"
+version = "1.8.0"
+
+[[source]]
+extract_dir = "$name-$version"
+url = "https://github.com/DentonW/DevIL.git#v$version"
+patches = [ "jasper.patch", "soversion.patch" ]
+
+[[manual_sources]]
+files = [ "jasper.patch", "soversion.patch" ]

extra/devil/jasper.patch

@@ -0,0 +1,35 @@
+--- a/DevIL/src-IL/src/il_jp2.cpp
++++ b/DevIL/src-IL/src/il_jp2.cpp
+@@ -313,14 +313,32 @@ }
+ 
+ 
+-
++// Hack to compile against different versions of Jasper which expect
++// slightly different function types for their callbacks.  The defined()
++// checks are just looking for sybols that happen to have arrived around
++// the same time as the API change, so no reason they won't break in the
++// future :-(  Hopefully by the time it does nobody will care about pre-2.0.20
++// versions of jasper
++//
++// see: https://github.com/OSGeo/gdal/commit/9ef8e16e27c5fc4c491debe50bf2b7f3e94ed334
++//      https://github.com/DentonW/DevIL/issues/90
++#if defined(PRIjas_seqent)
++static ssize_t iJp2_file_read(jas_stream_obj_t *obj, char *buf, size_t cnt)
++#else
+ static int iJp2_file_read(jas_stream_obj_t *obj, char *buf, int cnt)
++#endif
+ {
+ 	obj;
+ 	return iread(buf, 1, cnt);
+ }
+ 
++#if defined(JAS_INCLUDE_JP2_CODEC)
++static ssize_t iJp2_file_write(jas_stream_obj_t *obj, const char *buf, size_t cnt)
++#elif defined(PRIjas_seqent)
++static int iJp2_file_write(jas_stream_obj_t *obj, char *buf, unsigned cnt)
++#else
+ static int iJp2_file_write(jas_stream_obj_t *obj, char *buf, int cnt)
++#endif
+ {
+ 	obj;
+ 	return iwrite(buf, 1, cnt);

extra/devil/soversion.patch

@@ -0,0 +1,30 @@
+--- a/DevIL/src-IL/CMakeLists.txt
++++ b/DevIL/src-IL/CMakeLists.txt
+@@ -58,6 +58,7 @@ source_group("Text Files" FILES ${DevIL_TXT} )
+ 
+ if(BUILD_SHARED_LIBS)
+     add_library(IL SHARED ${DevIL_SRCS} ${DevIL_INC} ${DevIL_RSRC} ${DevIL_TXT})
++    set_target_properties(IL PROPERTIES SOVERSION 1)
+ else(BUILD_SHARED_LIBS)
+     add_library(IL ${DevIL_SRCS} ${DevIL_INC} ${DevIL_RSRC} ${DevIL_TXT})
+ endif(BUILD_SHARED_LIBS)
+--- a/DevIL/src-ILU/CMakeLists.txt
++++ b/DevIL/src-ILU/CMakeLists.txt
+@@ -44,6 +44,7 @@ source_group("Resource Files" FILES ${ILU_RSRC} )
+ 
+ # Remove SHARED to create a static library
+ add_library(ILU SHARED ${ILU_SRCS} ${ILU_INC} ${ILU_RSRC})
++set_target_properties(ILU PROPERTIES SOVERSION 1)
+ 
+ 
+ ## ILU requires IL
+--- a/DevIL/src-ILUT/CMakeLists.txt
++++ b/DevIL/src-ILUT/CMakeLists.txt
+@@ -44,6 +44,7 @@ source_group("Resource Files" FILES ${ILUT_RSRC} )
+ 
+ # Remove SHARED to create a static library
+ add_library(ILUT SHARED ${ILUT_SRCS} ${ILUT_INC} ${ILUT_RSRC})
++set_target_properties(ILUT PROPERTIES SOVERSION 1)
+ 
+ ## add link sub library info
+ target_link_libraries(ILUT