Add cross-platform include/lib/inttypes.h

Signed-off-by: Nikita 'webconn' Maslov <wkernelteam@gmail.com>
Rework tmgr library (issue #16) NEED TESTING

Features of reworked tmgr library:

* Cross-platform, tiny task manager/scheduler

* Two modes of operation: uptime-based (faster, but limited in device
uptime) and countdown-based (a bit slower, but uptime-independent)

* In uptime-based mode, the information about system uptime is available
and could be used in projects (for debugging, logging etc.)

* Time conversion functions (s/ms/us to timer ticks and vice versa)

* Basic delay implementation

Signed-off-by: Nikita 'webconn' Maslov <wkernelteam@gmail.com>