Initial commit: add code

- using meson build
 - implement shell using gobject API
 - support wlr-foreign-toplevel protocol
 - shell base UI (WIP)

meson.build

@@ -0,0 +1,59 @@
+project('diya-shell',
+    ['c'],
+    version: '0.1.0',
+    license: 'MIT',
+    meson_version: '>=0.51.0',
+    default_options: ['c_std=gnu11', 'warning_level=3'])
+
+lib_so_version = '0'
+
+add_project_arguments(
+    [
+        '-Wno-pedantic',
+        '-Werror=implicit-function-declaration',
+        '-Werror=return-type',
+    ],
+    language: 'c')
+
+gtk = dependency('gtk4')
+wayland_client = dependency('wayland-client', version: '>=1.10.0')
+
+# wayland_scanner is required, but we can find it without pkg-config
+wayland_scanner = find_program('wayland-scanner')
+
+# use system xdg-shell protocol when available
+#wayland_protocols = dependency('wayland-protocols', version: '>=1.16')
+
+# pkg_config = import('pkgconfig')
+# gnome = import('gnome')
+
+gtk_layer_shell = dependency('gtk4-layer-shell-0', version: '>=1.0.2')
+wayland_targets=[]
+
+wayland_protos = [
+  'protocols/wlr-foreign-toplevel-management-unstable-v1'
+]
+
+foreach proto : wayland_protos
+  xml  = ''.join([proto,'.xml']) 
+  header = ''.join([proto.split('/').get(-1),'.h'])
+  cfile = ''.join([proto.split('/').get(-1),'.c'])
+  wayland_targets += custom_target(header,output:header,input:xml,
+      command: [ wayland_scanner, 'client-header', '@INPUT@', '@OUTPUT@' ] )
+  wayland_targets += custom_target(cfile,output:cfile,input:xml,
+      command: [ wayland_scanner, 'public-code', '@INPUT@', '@OUTPUT@' ] )
+endforeach
+
+src = [
+    'src/base.c',
+    'src/launcher.c',
+    'src/background.c',
+    'src/wayland.c',
+    'src/shell.c',
+    'src/foreign.c',
+    wayland_targets]
+
+executable(
+    'diya-shell',
+    src,
+    dependencies: [gtk, gtk_layer_shell, wayland_client])