Don't use end-of-buffer-workaround

Instead, start the overlay one character earlier, if not at eob.

That also improves the situation with fci-mode (#180).
Use posn-actual-col-row to calculate the row

Approximation by `posn-col-row' is not good enough, particularly in the Log-Edit
buffer.
company-complete-number: Make interactive, read the pressed digit

Fixes #177.
company-gtags-modes: Turn into defcustom

Closes #178.
company-with-candidate-inserted: restore buffer modification status
Only use company-ropemacs when ropemacs-mode is on

Step 1 of moving company-ropemacs out, #159.
company--posn-col-row: add comment
Release 0.8.4