Rework the color option to support setting ANSI color code values
ranging from 0..255 or "none" for no color or "list" to print a list of
available ANSI colors codes.
Also, disables color when piping.
While in hex mode (ctrl-t h) you can output hexadecimal values.
E.g.: to send 0x0A you have to type 0A (always 2 characters).
Added option -x, --hex to start in hexadecimal mode.
Added option --newline-in-hex to interpret newline characters in hex mode.
This is disabled by default, because, in my opinion, hex stream is
fundamentally different from text, so a "new line" is meaningless in this
context.
Allow user to select which ANSI color code to use to colorize the tio
text. To successfully set the color the color code must be in the range
0..255.
If color code is negative tio will print all available ANSI colors.
The default color is changed to bold white to make tio defaults usable
for most users, including color blind users.
