switch to exceptions for error handling
fix format function naming and add hex input mode support
simplify cli options with output mode and input mode
add pts_shunt testing tool under misc/
remove unnecessary non-blocking flag in tty open

and handling in fd_read()
pass tty options by parameters to serial_open()
change to input and output pipeline architecture
remove unnecessary fd_read()/fd_write() wrapper functions
simplify color code character handling
add input and output processor unit tests
clarify transmit / receive newline substitutions in help
support non-tty standard input for piping
minor fixes to help/usage
update install prefix in Makefile to /usr
relicense under MIT license
update readme, changelog, program version to v2.0