Add files for testing

Most of these files are introduced from:
https://github.com/magnars/s.elmagnars/s.el
Remove functions: `move-to-first-window' and `hilight-line'

These are not used.
Rename and refactor functions

* jump-to-corresponding-line-in-po-file: was changed into
`show-po-file-smartly-in-other-window', which calls
`show1-po-file-other-window' with new parameter line-in-texi.
This removes `generate-seq' and `number-to-sting-array'.

* `my-po-move-in-texi-file-to-current-po-entry': was changed into
`my-po-current-entry-followed-by-recentered-texi-window'.