Audit updates

Audit updates

* rename HttpRequestMethod(char*) to HttpRequestMethodXXX() in order to
  assist removal since it is deprecated now
 - plus code polishing and unit-test updates to work with this as a
   method instead of constructor

* fix several potential out-of-bounds SBuf and MemBlob accesses

* reduce performance regression parsing ICAP/eCAP traffic

* simplify and optimize clear() operation

* documentation clarifications

* typos and spelling fixes