Bugfixes and API additions

1. Add AXIOM API for fetching previous and next sibling elements. Useful when we want to skip XML whitespace nodes constructed as AXIOM_TEXT.
2. Add API for removing fault from SOAP Body. This is needed by e.g. Rampart in case we are encrypting SOAP body, thus destroying its nested fault structure.
3.Fix a bug when using SOAP 1.1. Fault conversion from SOAP 1.2 to 1.1 was occurring too late - the SOAP body could have already been encrypted by Rampart. In this case Axis2/C crashed because of a dangling reference.
4.Add API for retrieving dep_engine from conf. Useful when embedding Axis2/C (e.g. when svc implementation is in the loading process instead of the shared library).
5.Fix fault value in case SOAP 1.1. is used. I am not clear why this code was here in the first place. It seems to have been intentionally added, but reason for this inaccuracy eludes me.
6.Set dep_engine to conf as soon as dep_engine is created. A lot of code expects that conf has dep_engine available and causes a crash.

These are independent of one another and can be applied separately.