Revert "Restore selected window in set-window-configuration"

This reverts commit a89046024a7cd6e7327382b15947cc6715ba0c5f.

This fixes some mysterious errors:

- When opening latex file first time, Emacs fails to switch to the
  opened file buffer.  Also, the buffer I was in *before* opening the
  buffer turns into latex-mode.

- When exporting org-mode file (C-c C-e C-h), exported file content
  is inserted into the current buffer.