I made function list suggestion and description tip in libreoffice calc.
This change give us a nice function suggestion and easy function input.
For example if I write "=i" then calc suggests
"[if], iferror, ifna, and 50 more". You should only choice the function
you would write with Ctrl-Tab and Ctrl-Shift-Tab, and then type Enter.
Also there is a description of suggesting function, so even if you
do not know the true name of the function you want to write, you can
find the function.
This change also give us a description of arguments of selected function.
If I write "=i" and push enter key, then calc show "=if()" and
a description of arguments of function "if()".

Change-Id: Icd5ad04ea092fa39f27bb2776fd9e93649896baf
Reviewed-on: https://gerrit.libreoffice.org/20035Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>