CLI: TCPF: Developing

*Splitting some big commit*
Move declarations between header files
CLI: TCPF: Developing

Remove redundant tcpf_client_end()
CLI: TCPF: Developing

Migrating client to the new logic. The client uses some server
functions, for example: tcpf_select(), read_frame(), parse_frame.
This makes possible to avoid repeating of some code. Need
to make a new file with 'common' functions to make the code cleaner.
CLI: TCPF: Development

Migrate tcpf_gen_skey() to the library.
CLI: TCPF: Development

Make tcpf_flush_frame_buffer() and move it to the library.