Fix Doxygen generation instead of working around incorrect output

Make Doxygen ignore `G_{BEGIN,END}_DECLS` and `GEANY_API_SYMBOL` itself
instead of stripping those manually when parsing the XML output.

This makes Doxygen parsing more robust by ignoring some odd C syntax,
and also improves the HTML version removing some incorrect C code
references.

doc/Doxyfile.in

@@ -2035,7 +2035,10 @@ INCLUDE_FILE_PATTERNS  =
 # This tag requires that the tag ENABLE_PREPROCESSING is set to YES.
 
 PREDEFINED             = "G_GNUC_PRINTF(x,y)=" \
+                         G_BEGIN_DECLS= \
+                         G_END_DECLS= \
                          HAVE_PLUGINS \
+                         GEANY_API_SYMBOL= \
                          GEANY_FUNCTIONS_H
 
 # If the MACRO_EXPANSION and EXPAND_ONLY_PREDEF tags are set to YES then this

scripts/gen-api-gtkdoc.py

@@ -281,7 +281,7 @@ class DoxyTypedef(DoxyElement):
     @staticmethod
     def from_memberdef(xml):
         name = xml.find("name").text
-        d = normalize_text(xml.find("definition").text).replace("G_BEGIN_DECLS", "")
+        d = normalize_text(xml.find("definition").text)
         d += ";"
         return DoxyTypedef(name, d)
 
@@ -338,9 +338,9 @@ class DoxyFunction(DoxyElement):
     @staticmethod
     def from_memberdef(xml):
         name = xml.find("name").text
-        d = normalize_text(xml.find("definition").text.replace("G_BEGIN_DECLS", ""))
+        d = normalize_text(xml.find("definition").text)
         d += " " + xml.find("argsstring").text + ";"
-        d = normalize_text(d.replace("GEANY_API_SYMBOL", ""))
+        d = normalize_text(d)
 
         e = DoxyFunction(name, d)
         e.add_brief(xml.find("briefdescription"))
@@ -385,7 +385,7 @@ def main(args):
     for f in h_files:
         if not (f.find("compoundname").text.endswith("private.h")):
             for n0 in f.xpath(".//*/memberdef[@kind='typedef' and @prot='public']"):
-                if not (n0.find("type").text.replace("G_BEGIN_DECLS", "").lstrip().startswith("enum")):
+                if not (n0.find("type").text.startswith("enum")):
                     e = DoxyTypedef.from_memberdef(n0)
                     typedefs.append(e)