[OpenSER-Docs] Doc Improvements

I know that just now we are dealing with SGML to XML conversion, but it seams that some point have to be registered: 1- clearer documentation/explanation of the functions internals. Specifically what they do and what they changes (SIP messages, internal counters/timers, PV, AVP, etc). 2- make very clear which functions break normal script execution (p.ex. see the "noisy_ctimer" parameter in TM module" discussion). And to close a question: Should the DOC volume include the Doxigen documentation? Where? In a hole dedicated and separete chapter, or should each module have in it's documentation another chapter/section just for dealing with this internal informations? I, particularly would like to see the generated graphs being merged just after the function/parameter explanation (just for the external/exported functions/parameters/variables). Edson.