Added basic logic for :autocmd.
Added utility function for wildcard matching.
Don't put autocmd commands in history.
Merge branch 'master' into feature/autocmd

Conflicts:
	src/ex.c
Merge branch 'master' into feature/autocmd
Allow multiple autocmd patterns (#100).
Allow to remove augroup (#100).
Faster return for wildmatch with trailing '*'.

If the pattern ends in '*' it's not necessary to call the wildmatch, because
this will match everything.
Store the used autocmd event bits (#100).

The bits of the used autocmd events are now stored in a variable to early
break out of the autocmd, if there is no autocmd defined for a particular
event.
Added more test cases for multiple * and ? in pattern.
Added curly brace pattern matching for auto commands (#100).

This allows to match pattern with {foo,bar} to match 'foo' or 'bar'. This is
really useful for protocol matching for examaple
http{s,}://{www,mail,maps}.ugly-domain.com/*.
Allow to match multiple patterns (#100).

Change the matching functions to not end at the NUL of the pattern. In stead
we give a pattern length parameter. This allows to process multiple patterns
without the need to put NUL-bytes into it or to allocate memory for the parts
to match.
Shortened the autocmd event names (#100).

This makes the config easier to maintain.
Fixed compiler warning if autocmd feature is disabled (#100).
Fixed possible use of uninitialized variable.
Use for loops instead of while.
Added section about autocmd to man page (#100).
Don't provide uri for LoadProvisional event (#100).
Added autocmd events for downloads (#100).
Change autocmd_run function signature.

This leads to easier read code, because we don't need to use NULL as first
function parameter.