Add gdbus-codegen(1) command

It doesn't work yet without the user manually adding ffi bits. That's
the topic of the next commit.

Signed-off-by: David Zeuthen <davidz@redhat.com>

gio/gdbus-codegen/utils.py

@@ -0,0 +1,56 @@
+# -*- Mode: Python -*-
+
+def strip_dots(s):
+    ret = ''
+    force_upper = False
+    for c in s:
+        if c == '.':
+            force_upper = True
+        else:
+            if force_upper:
+                ret += c.upper()
+                force_upper = False
+            else:
+                ret += c
+    return ret
+
+def dots_to_hyphens(s):
+    return s.replace('.', '-')
+
+def camel_case_to_uscore(s):
+    ret = ''
+    insert_uscore = False
+    prev_was_lower = False
+    for c in s:
+        if c.isupper():
+            if prev_was_lower:
+                insert_uscore = True
+            prev_was_lower = False
+        else:
+            prev_was_lower = True
+        if insert_uscore:
+            ret += '_'
+        ret += c.lower()
+        insert_uscore = False
+    return ret
+
+def lookup_annotation(annotations, key):
+    if annotations:
+        for a in annotations:
+            if a.key == key:
+                return a.value
+    return None
+
+def lookup_docs(annotations):
+    s = lookup_annotation(annotations, 'org.gtk.GDBus.DocString')
+    if s == None:
+        return ''
+    else:
+        return s
+
+def lookup_brief_docs(annotations):
+    s = lookup_annotation(annotations, 'org.gtk.GDBus.DocString.Short')
+    if s == None:
+        return ''
+    else:
+        return s