drop python-xlib

[seebye]

Python-xlib misses some essential features like shm support.
This is why the Xshm module was written,
but this leads to redundant dependencies.
So this commit removes python-xlib as dependency.

During the translation of the code the determination of the pid of a
window was also improved.
The XRes extension is now used to determine the pid of a window.

[mehalter]

I am getting errors after this merge when building ueberzug (before this was merged to master I do not get errors while buiilding). I am trying to build this on Arch linux with libxres installed and I am getting the following error when it tries to build the ueberzug.X extension:

building 'ueberzug.X' extension
gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -march=x86-64 -mtune=generic -O3 -pipe -fno-plt -fno-semantic-interposition -march=x86-64 -mtune=generic -O3 -pipe -fno-plt -march=x86-64 -mtune=generic -O3 -pipe -fno-plt -fPIC -Iueberzug/X -I/usr/include/python3.9 -c ueberzug/X/X.c -o build/temp.linux-x86_64-3.9/ueberzug/X/X.o
gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -march=x86-64 -mtune=generic -O3 -pipe -fno-plt -fno-semantic-interposition -march=x86-64 -mtune=generic -O3 -pipe -fno-plt -march=x86-64 -mtune=generic -O3 -pipe -fno-plt -fPIC -Iueberzug/X -I/usr/include/python3.9 -c ueberzug/X/Xshm.c -o build/temp.linux-x86_64-3.9/ueberzug/X/Xshm.o
gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -march=x86-64 -mtune=generic -O3 -pipe -fno-plt -fno-semantic-interposition -march=x86-64 -mtune=generic -O3 -pipe -fno-plt -march=x86-64 -mtune=generic -O3 -pipe -fno-plt -fPIC -Iueberzug/X -I/usr/include/python3.9 -c ueberzug/X/display.c -o build/temp.linux-x86_64-3.9/ueberzug/X/display.o
ueberzug/X/display.c:214:1: warning: ‘Display_get_screen_height’ defined but not used [-Wunused-function]
  214 | Display_get_screen_height(DisplayObject *self, void *closure) {
      | ^~~~~~~~~~~~~~~~~~~~~~~~~
gcc -pthread -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -march=x86-64 -mtune=generic -O3 -pipe -fno-plt -fno-semantic-interposition -march=x86-64 -mtune=generic -O3 -pipe -fno-plt -march=x86-64 -mtune=generic -O3 -pipe -fno-plt -fPIC -Iueberzug/X -I/usr/include/python3.9 -c ueberzug/X/window.c -o build/temp.linux-x86_64-3.9/ueberzug/X/window.o
gcc -pthread -shared -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -fno-semantic-interposition -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now build/temp.linux-x86_64-3.9/ueberzug/X/X.o build/temp.linux-x86_64-3.9/ueberzug/X/Xshm.o build/temp.linux-x86_64-3.9/ueberzug/X/display.o build/temp.linux-x86_64-3.9/ueberzug/X/window.o -L/usr/lib -lX11 -lXext -lXRes -o build/lib.linux-x86_64-3.9/ueberzug/X.cpython-39-x86_64-linux-gnu.so
/usr/bin/ld: build/temp.linux-x86_64-3.9/ueberzug/X/Xshm.o:/home/micah/TEST/ueberzug/ueberzug/X/display.h:27: multiple definition of `DisplayType'; build/temp.linux-x86_64-3.9/ueberzug/X/X.o:/home/micah/TEST/ueberzug/ueberzug/X/display.h:27: first defined here
/usr/bin/ld: build/temp.linux-x86_64-3.9/ueberzug/X/Xshm.o:/home/micah/TEST/ueberzug/ueberzug/X/Xshm.c:279: multiple definition of `ImageType'; build/temp.linux-x86_64-3.9/ueberzug/X/X.o:/home/micah/TEST/ueberzug/ueberzug/X/Xshm.h:6: first defined here
/usr/bin/ld: build/temp.linux-x86_64-3.9/ueberzug/X/display.o:/home/micah/TEST/ueberzug/ueberzug/X/display.h:27: multiple definition of `DisplayType'; build/temp.linux-x86_64-3.9/ueberzug/X/X.o:/home/micah/TEST/ueberzug/ueberzug/X/display.h:27: first defined here
/usr/bin/ld: build/temp.linux-x86_64-3.9/ueberzug/X/window.o:/home/micah/TEST/ueberzug/ueberzug/X/display.h:27: multiple definition of `DisplayType'; build/temp.linux-x86_64-3.9/ueberzug/X/X.o:/home/micah/TEST/ueberzug/ueberzug/X/display.h:27: first defined here
/usr/bin/ld: build/temp.linux-x86_64-3.9/ueberzug/X/window.o:/home/micah/TEST/ueberzug/ueberzug/X/window.c:299: multiple definition of `WindowType'; build/temp.linux-x86_64-3.9/ueberzug/X/X.o:/home/micah/TEST/ueberzug/ueberzug/X/window.h:6: first defined here
collect2: error: ld returned 1 exit status
error: command '/usr/bin/gcc' failed with exit code 1