[FEATURE] Chunk ViewHelper

array_chunk() is a really helpful function which functionality should be available as a ViewHelper.

Fx if you have an Array of pages from v:page.menu and want to allocate these links to a fixed number of container elements this would be much code without this ViewHelper.

Fx we have 9 links which shall be placed in 2 containers of same count of items each, if odd the first container takes more all.

Expected html markup:
<div class="container1">
<a>1. Link</a>
<a>2. Link</a>
<a>3. Link</a>
<a>4. Link</a>
<a>5. Link</a>
</div>
<div class="container2">
<a>6. Link</a>
<a>7. Link</a>
<a>8. Link</a>
<a>9. Link</a>
</div>

With this ViewHelper this is an easy task:
{links->v:iterator.chunk(count:2,fixed:1)->v:var.set(name:'chunks')}
<div class="container1">
<f:for each="{chunks.0}" as="item">{item}</f:for>
</div>
<div class="container2">
<f:for each="{chunks.1}" as="item">{item}</f:for>
</div>
[BUGFIX] Use ctype_digit instead of is_numeric

The is_numeric function returns TRUE on fx string "z123" which ctype_digit does not - it's preferable to return FALSE on strings like this.
[BUGFIX] Use PREG_SET_ORDER on preg_match_all

This causes the $matches array to be filled in a way which allows the subsequent conditions to function properly when $global = TRUE.
[BUGFIX] Abstract Iterator returns FALSE if item is in position zero

Casting to boolean replaced with check for strict FALSE !==.
[BUGFIX] Single Math ViewHelpers used incorrect value when $a is Iterator
[BUGFIX] Multiple Math ViewHelpers used incorrect value when $a is Iterator
[BUGFIX] Multiple Math ViewHelpers performed Iterator access check on non-Iterators
[BUGFIX] Math / Median uses incorrect slicing point and midpoint calculation
[BUGFIX] Ensure consistent return type in Math / Range ViewHelper
[BUGFIX] Var / Convert used incorrect ObjectStorage check and conversion
[TASK] Various cleanups and optimisations without changing any behavior
[TASK] Massive cleanup and improvement to tests in multiple namespaces
[BUGFIX] Fix 'as' argument

The as argument was not accessible, as the method signature and Doc-Comment was missing it
Merge pull request #333 from NamelessCoder/cleaning

[TASK] Numerous bugfixes, cleanups and test improvements
Merge pull request #334 from cedricziel/sliceFix

[BUGFIX] Fix 'as' argument
[BUGFIX] Avoid overwriting of menu items with same page uid
[BUGFIX] Special treatment for raw assets
Merge pull request #338 from bjo3rnf/browsefix

[BUGFIX] Avoid overwriting of menu items with same page uid
Merge pull request #339 from bjo3rnf/rawfix

[BUGFIX] Special treatment for raw assets
[BUGFIX] Fix missing parameter which causes the child element not to be appended.