proxy support for civis and cnorm on 'ansi' terms.

Although many 'ansi' emulating terminals support
show/hide cursor (fe. SyncTerm), the terminfo db
does not contain any entry. Provide proxy support
in the same way that move_{x,y} is provided for
terminals of type 'screen'
Merge pull request #22 from jquast/proxy-ansi-support-for-cursor

proxy support for civis and cnorm on 'ansi' terms.