Moving syscalls to the root directory. It can't be the part of library and has to be compiled and linked with the actually application code.
Added 2 functions accessible from C that use the singleton object of UART class for data io.
Reimplementing newlib _write and _read using the redirect_read/write api from nrfpp.
Also stripped the code, got rid of the unused stuff.
syscalls.h is not used anymore.
Added the following compiler options:
  -Os -flto -ffunction-sections -fdata-sections -fno-builtin
and linker options:
  -Wl,--gc-sections -flto

This resulted in very dramatic reduction of the code size!
Adding syscalls.c which contains the reimplementation of newlib's _write, _read, etc.
Using a higher speed communication and sending the data more often.
Removed incorrect/redundant stuff.