Allow setting cursor color with escape sequence again.
This commit 97feb543 broke support for changing cursor color by escape sequence if value starts with CursorShape=
.
I was using let &t_SI = "\<Esc>]50;CursorShape=1;CustomCursorColor=\#ff5f00\x7"
which worked until the 97feb543 change.
This MR implements support for setting cursor color and also for cursor blinking without changing the current profile what is purpose of the 97feb543 change.