Minor corrections in Makefiles.
Replaced LDDEPS by LDLIBS in build environment. Added support for prebuilt libraries.
Enabled atmega8 for UART.
Added dual-port functionality to UART driver. Driver functions can be safely called from within ISRs if UART_INTERRUPT_SAFETY is enabled.
Adapted command line subsystem for the new UART driver interface.
Renamed macro: UART_ENABLE_RX_CALLBACK_NESTED_INTERRUPT -> UART_ENABLE_RX_CALLBACK_NESTED_INTERRUPTS
Adjusted applications to meet the new uart/cmdl interface.
Introduced typedef for UART interface identifier.
Merge branch 'feature/dual_uart' into develop