[FEATURE] Add page link ViewHelper

This ViewHelper is an alternative to <f:page.link /> that fetches the linked page title and inserts it as link text as proposed in #240.
[TASK] Respect hideNotTranslated setting
[TASK] Add titleFields argument
[DOC] Correct return value description
[TASK] Make use of registerArguments to improve legibility
[TASK] Use proper string concatenation to reduce line lengths
[TASK] LTS compatibility in If / Condition ViewHelper

Introduce a wrapper method to ensure a RenderingContext is returned on LTS as well as 6.0+.

Fixes: #144
[TASK] Adhere coding guidelines
Merge pull request #244 from NamelessCoder/contextwrap

[TASK] LTS compatibility in If / Condition ViewHelper
Merge pull request #242 from bjo3rnf/autolink

[FEATURE] Add page link ViewHelper
[BUGFIX] Ensure global assets array exists
Merge pull request #245 from bjo3rnf/assetsarray

[BUGFIX] Ensure global assets array exists