+ Add system timestamps to lua read() and new lua read_line() per global options

+ Add missing timestamp-format epoch
+ Update send_ to use fsync and tcdrain like normal tty_sync does
+ Rework read_line to save partial line at timeout
+ Simplified read_line to reduce cyclomatic complexity

+ renamed example files read.lua and read_line.lua
+ moved #define READ_LINE_SIZE to top of file
+ renamed g_linebuf to linebuf, and moved it into read_line as a static variable

man/tio.1.in

@@ -467,7 +467,18 @@ until data is ready to read.
 
 Returns number of bytes read on success, 0 on timeout, or -1 on error.
 
-On success, returns read string as second return value.
+On success, returns read string as second return value.  Also emits a single
+timestamp to stdout and log file per options.timestamp and options.log.
+
+.IP "\fBread_line(timeout)"
+Read line from serial device. If timeout is 0 or not provided it will wait
+forever until data is ready to read.
+
+Returns number of bytes read on success, 0 on timeout, or -1 on error.
+
+On success, returns the string that was read as second return value.  Also
+emits a single timestamp to stdout and log file per options.timestamp
+and options.log.
 
 .IP "\fBset{line=state, ...}"
 Set state of one or multiple tty modem lines.