This callback is *always* called, including when there has been an
error.
This is in preparation for making text_from_{clipboard,primary}
asynchronous.
We do however need access to it, so provide a pointer. The difference
is that now we can have a *single* wayland instance, but multiple
terminal instances.
That is, remove the 'regular' and 'bright' color arrays. This is
possible since the 256-color array is defined such that the first 16
colors map to the regular and bright colors.
This implements OSC 4, 10, 11 - change <color>/foreground/background,
and their corresponding 'query' variant (which was already implemented
for OSC 10/11).
It also implements OSC 104, 110, 111 - reset
<color>/foreground/background.
Set corresponding terminfo entries to signal this support to clients.
When responding to a OSC 52 clipboard request, we need to base64
encode the clipboard data.
This is done in, potentially, several calls. Since we need at least 3
bytes to be able to produce any base64 output, we may have to buffer
up to 2 bytes between the callback calls with clipboard data.
This was being done incorrectly, where both bytes were written to
index 0 in the buffer.
Replace with generic error log messages that simply says the
ESC/CSI/OSC sequence is unhandled. This can mean either invalid or
unimplemented, depending on the context.
* action() returns void - this gets rid of checks in vt_from_slave()
* split up ACTION_PRINT into ACTION_PRINT (ASCII) and ACTION_UTF8_PRINT
ACTION_PRINT is on the hot path, and we want it streamlined.
* Remove run-time checkout for unimplemented state transitions, as we
shouldn't have any of those left.
* Don't re-load current VT state on each iteration in vt_from_slave()
