Problem: Tabs are not aligned when scrolling horizontally and a Tab doesn't
fit. (Axel Bender)
Solution: Handle a Tab as a not fitting character. (Christian Brabandt)
Also fix that ":redraw" does not scroll horizontally to show the
cursor. And fix the test that depended on the old behavior.
Problem: Test_help_complete sometimes fails in MS-Windows console.
Solution: Use getcompletion() instead of feedkeys() and command line
completion. (Hirohito Higashi)
