[Fix #57] Guard the definition of fringe bitmaps
Put first checker error on top

Add overlays from last to first error so that for each error region the
first error emitted by the checker is stacked on top.
Do not mess up error match data

s functions may change the match data, thus we need to restore this
match data in order to safely continue error parsing afterwards.

Why oh why did they make the match data global?!  Now I just hate you,
dear Emacs…
Fix arguments of Emacs Lisp checker

The checker needs something to check, really…
Handle unbound no-byte-compile in Emacs Lisp predicate
Fix argument order for s-ends-with?

See bbatsov/prelude#253
Highlight column on empty line correctly

If an error refers to a column on an empty line, highlight from the end
of the previous line.

Also simplify `flycheck-error-region`.
Highlight errors beyond end of line correctly