Doxygen: get some html output again

It looks like Doxygen no longer recognizes our pure C headers without us
adding a lot of Doxygen markers. Since we have neither the time nor the
desire to dance to the tune of a documentation tool, we try to squeeze
more output out of the tool with the crowbar. If this doesn't really add
value, we will simply drop the doxygen configuration.

Fixes: #244
Signed-off-by: Patrick Bruenn <p.bruenn@beckhoff.com>

Author: pbruenn

docs/Doxyfile

@@ -398,7 +398,7 @@ LOOKUP_CACHE_SIZE      = 0
 # normally produced when WARNINGS is set to YES.
 # The default value is: NO.
 
-EXTRACT_ALL            = NO
+EXTRACT_ALL            = YES
 
 # If the EXTRACT_PRIVATE tag is set to YES all private members of a class will
 # be included in the documentation.
@@ -743,7 +743,7 @@ WARN_LOGFILE           =
 # spaces.
 # Note: If this tag is empty the current directory is searched.
 
-INPUT                  = docs/mainpage.dox AdsLib/AdsDef.h AdsLib/AdsLib.h
+INPUT                  = docs/mainpage.dox AdsLib
 
 # This tag can be used to specify the character encoding of the source files
 # that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses