Added ability to build with GSL

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Drop leftover

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Split off logging functions

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Splitted off string-related functions

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Split off time-related functions

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Split off socket-related functions

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Split off SIP mini-parser

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Move more screen-related functions to screen.cpp

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>
Split off unit-tests from the main module

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>