Remove command-line option inconsistencies

Optional arguments, as parsed by the getopt_long mechanism, are
inherently inconsistent with how you define required arguments.

To avoid confusion we decide to avoid this inconsistency by replacing
optional options with additional options with required argmuments.

man/tio.1.in

@@ -57,9 +57,14 @@ option is provided, tio will exit if the device is not present or an established
 Enable local echo.
 
 .TP
-.BR \-t ", " \-\-timestamp[=\fI<format>\fR\fB]
+.BR \-t ", " \-\-timestamp
 
-Enable timestamp. Optionally you can specify any of the following timestamp formats:
+Enable line timestamp.
+
+.TP
+.BR "    \-\-timestamp-format \fI<format>
+
+Set timestamp format to any of the following timestamp formats:
 .RS
 .TP 16n
 .IP "\fB24hour"
@@ -79,9 +84,14 @@ Default format is
 List available serial devices.
 
 .TP
-.BR \-l ", " \-\-log[=\fI<filename>\fR\fB]
+.BR \-l ", " \-\-log
 
-Log to file. If no filename is provided the filename will be automatically generated.
+Enable log to file. If no filename is provided the filename will be automatically generated.
+
+.TP
+.BR "    \-\-log-filename \fI<filename>
+
+Set log filename.
 
 .TP
 .BR \-m ", " "\-\-map " \fI<flags>
@@ -188,6 +198,7 @@ Options without any config section name sets the default options.
 .TP
 The following configuration file options are available:
 
+.TP 20n
 .IP "\fBpattern"
 pattern matching user input. This pattern can be an extended regular expression with a single group.
 .IP "\fBtty"
@@ -207,13 +218,15 @@ Set output delay
 .IP "\fBno-autoconnect"
 Disable automatic connect
 .IP "\fBlog"
-Log to file
+Enable log to file
 .IP "\fBlog-filename"
 Set log filename
 .IP "\fBlocal-echo"
 Enable local echo
 .IP "\fBtimestamp"
-Prefix each new line with a timestamp
+Enable line timestamp
+.IP "\fBtimestamp-format"
+Set timestamp format
 .IP "\fBmap"
 Map special characters on input or output
 .IP "\fBcolor"