Implemented usart.h----> Declarated In-line functions write, read, enable2xMode, enable, disable, baudRate.
                         Redefined functions using traits
Included interruptMgr.cpp
Included interruptMgr.h
Created --> serial.cpp & serial.h: class to use serial communication through usart ports

added --> stl files to be included in the rest of the project
Merge branch 'master' of https://github.com/technik/bbduino