applications: added common copyright headers.
DHCP: data members are grouped together according to their role (state, parameter, statistic)
SCTPApplications: code refactoring

- added TODOs
- renamings
- improved readability in the class declaratation
SCTPApplications: uint32, uint64, int32, etc. replaced with their corresponding C++ types.
SCTPApplications: removed some unused functions.
SCTPApplications: fixed a memory leak issue and uninitialised msg pointers.
SCTPApplications: removed a lot of explicit type-casts.
SCTPApplications: cosmetics
SCTPApplications: memory deallocation was simplified and moved to the destructor
SCTPApplications: comments & reorganize:
- internal methods shouldn't be documented
- changed the order of the declarations
RTPApplication: removed _ prefix from variables names, comments.
RTPApplication: added constructor to set member ptrs to NULL.
RTPApplication: just changed the order of the declarations.
PingApps, UDPApps, RTPApp: reorganized class declarations & code style
RTPApp: fixed constructor.
Application: reorganized class declarations.
HttpBrowserBase: fixed memory leaks. Base class constructor will be called automatically.
HttpBrowser: deleted an unused variable, memory deallocation moved to the destructor, comments.
HTTPTools: simple refactoring
HttpServerBase: added destructor and constructor.