Add build system.
Replace sp_set_params with sp_set_config, which takes a struct.
Use negative values in sp_port_config to retain existing settings.
Move cfset{i,o}speed() calls to set_baudrate().
New API for serial control lines.
Retrieve current control line settings in start_config.
Add prototypes for config helper functions.
Apply sane termios settings at port open time.
Add functions for setting individual port parameters.
Split up prototypes in include file for clarity.
Store control bits in sp_port_data on Unix.
Add sp_set_flowcontrol helper function.
Eliminate lengthy switch/case blocks for baudrates.
Remove disused flowcontrol field from sp_port_config.
Update documentation.