Create initial version of client

This just connects to the server and does very little else.

client/meson.build

@@ -0,0 +1,18 @@
+project(
+  'study-system-client',
+  'vala',
+  version : '0.1.0',
+)
+
+# Vala often generates C code that produces warnings, so ignore these
+# to avoid a noisy build output.
+add_project_arguments('-w', language: 'c')
+
+gtk_dep = dependency('gtk4')
+
+exe = executable(
+  'study-system-client',
+  'main.vala',
+  dependencies: [gtk_dep],
+  c_args: ['-w']
+)