[FEATURE] Attribute "as" on all menu ViewHelpers

Use of this argument allows setting the name of the variable that should contain the menu structure (note: in addition to the "menu" variable).
[BUGFIX] Inject missing ConfigurationManager in Render / Request
[BUGFIX] Early return in LanguageMenu ViewHelper if BE or missing object
[TASK] Add basic unit tests as generated by EXT:builder

This may very well be improved upon later but for now, it adds ~36% coverage to __the entire__ code base of EXT:vhs which is definitely a start :)
[TASK] Adjusted and protected tests which require special env
[TASK] Adjusted two remaining special env ViewHelper tests
[TASK] Adjust and protect more generated tests
Merge pull request #224 from NamelessCoder/tests

[TASK] Add a great big set of initial unit tests for ViewHelpers
[BUGFIX] Detect subpages using original page UID

When useShortcutUid or useShortcutData is set to TRUE detection of subpages was based on the overwritten page UID which is not desired
[TASK] Make property movable default to FALSE for CSS assets
[TASK] Make use of setter
[TASK] Typo in docblock
[TASK] Reorder getters and setters
Merge pull request #223 from NamelessCoder/as

[FEATURE] Attribute "as" on all menu ViewHelpers
Merge pull request #227 from bjo3rnf/movethatasset

[TASK] Add CSS assets to header by default
[BUGFIX] Relocate fetching of "as" on DeferredMenu
[BUGFIX] Respect argument showHidden when detecting subpages

Hidden pages (nav_hide=0) were always excluded from subpage detection even with showHidden=TRUE.
Merge pull request #229 from bjo3rnf/hiddenfix

[BUGFIX] Respect argument showHidden when detecting subpages
[BUGFIX] Correct parsing of argument doktypes

Fixes #228
Merge pull request #226 from bjo3rnf/menufix

[BUGFIX] Detect subpages using original page UID