[dev] [st] Statusline terminfo entries patch

Hi,

Attached is a patch to add terminfo entries asserting st has indeed an
statusline (i.e. you can change the window title) and how to write to
it. The code to do so is already there, but it has not been properly
specified in the terminfo file. Some software (e.g. sandy O:-)) uses
those entries to write to the statusline without hardcoding the escape
sequences used to get to/from there; other software should probably do
this instead of assuming xterm compatibility straight forward.

For some reason I fail to understand, this is not standard in the
"xterm" terminfo file, but is instead in "xterm+sl". It is also there
in "rxvt-unicode-256color", which is what my current terminal uses. If
anyone knows of a good reason to avoid this, please let me know so I
can scrap this patch and thik of something else for sandy.

Best regards,
Rafa.