[TASK] Refactor menu parsing

Menu items array is now indexed by page UID to help accessing single items in other view helpers
[FEATURE] Add browse menu view helper

This view helper adds a browse menu similar to special.browse in TS
[DOC] Update link to ViewHelpers
[DOC] Move ViewHelper reference link up after Wiki link
[TASK] Back up and restore variable "menu" by default in Menu ViewHelpers
[TASK] Set variable backup/restore in main Menu ViewHelper
[TASK] Set variable backup in Menu / BreadCrumb ViewHelper
[DOC] Adjust argument descriptions for defaults in Browse Menu ViewHelper
[TASK] Refactor link text fetching to shared method, Abstract Menu ViewHelper
[FEATURE] Allow getting title of pages from page record, Browse Menu ViewHelper
Merge pull request #3 from NamelessCoder/vhbrowse

[TASK] Few improvements to Browse Menu ViewHelper
Merge pull request #85 from dreipunktnull/vhbrowse

[FEATURE] Add browse menu viewhelper
[BUGFIX] Undesired Asset ViewHelper instance reuse avoided by clone

This fixes an issue where multiple assets added in the same context (for example inside the same Fluid f:section) would not be included properly.

The cause was an unfortunate mix of Fluid wanting to reuse the ViewHelper instance rather than creating a new one - and VHS wanting to save a reference to the current ViewHelper rather than a clone.

By simultaneously using `clone $this` before finalising each Asset and resetting cached settings in internal properties, instance uniqueness has been achieved.