MT#56128 Re-order option flags in the alphabet sequence

The option flags used when calling the rtpengine_offer()
have been re-ordered in the ascent manner according to alphabet.

Additionally three sub-sections have been created, to make
the sorting of flags simpler:
- Optionally included flags
- Optionally included replace-flags
- Optionally included codec manipulations

All subsection are also ordered inside.

Change-Id: I67663827eb710564f0314d1f6919d428206e1cef