Issue 415: No-folding configuration ignored.

When g:vimwiki_folding is set to '' there should be no folding no matter
what foldmethod you have in your .vimrc.
support for numbered lists and much other list stuff
Fix marker adjustment on gll
Level decrease binding was wrong.
Add some list bindings.
Do not add multiple * on gll

Lists in default vimwiki syntax has no multiple * as bullet point.
This behaviour could be implemented for media syntax.
Issue 2: g:vimwiki_rxListBullet is not defined

Move g:vimwiki_rxListBullet definition to corresponding syntax files.

Restore multiple bullets (*, **, ***) functionality, set up vimwiki
default lists have only one bullet.
Update list mappings.
Typo.
Change some list mappings to have prefix <C-L>.

Remove <C-B>, <C-S> and <C-A> mappings. Use <C-L><C-M>, <C-L><C-K>,
<C-L><C-J> instead.
Move around and simplify the code for initialization
Do not load whole syntax file for a buffer twice.

Load twice only regexes for a concrete syntax.
Simplify detection if two markers have same kind

Ref #5
Clean up messy function and fix i_<S-CR> sometimes not working
normal behavior of i_<C-T> and i_<C-D> when not on list item
Revert more of my earlier commit in order to fix #6
Issue 4: List folding doesn't work

Using new list functions to determine list fold level.
As a regression there is no folds for multilined list item's text.

1. item 1
2. item 2
   multilined
	 that is not
	 folded now
3. item 3

Previous method was able to fold item 2. I am not sure if we should fix
it or not.
Code clean up

Remove unused list functions from ftplugin.
Never alter a checkbox if it has no children with checkboxes
Fix checkboxes not getting updated in some cases