This causes colors that are set that are low numbered to
be treated as themed colors -- basically honoring the palette
of the terminal.
The Style and Color implementations have changed quite a bit
to permit growth -- the colors are now 64-bits wide to permit
using the upper bits as flags, and to leave room for a future
alpha channel.
There is a new TrueColor() method on colors that obtains the
value as strict RGB value, and this will be used in lieu of
whatever terminal colors are provided -- giving the application
full control over the color space if they want, without
forcibly clobbering user preferences for terminals for the
vast majority of cases.
Indexed colors are created with the new PaletteColor API.
Add a Beep() method to the Screen interface. On *nix systems, this
writes the bell character (0x07) to the tty. On Windows, we call the
MessageBeep syscall.
Fixes: #2
This expands support for 24-bit color for terminals that support the
ISO 8613-6:1994 escape sequences (same as xterm), allowing this support
to be enabled by setting % COLORTERM to "truecolor" (or 24bit or 24-bit),
or by setting TCELL_TRUECOLOR to "on", or by setting $TERM a value that
ends in the word "-truecolor".
As this is handled by the runtime now, we no longer need to create magical
database entries for -truecolor options.
A colors.go demo is provided to show off 24-bit color support.
fixes#38 Broke wide characters in last update
fixes#39 Clean up logic for encodings, enhance fallback options
fixes#36 Support more mouse buttons on Windows.
