Fix HTMLText AbsoluteLinks not parsing placeholder

Add an AbsoluteLinks method to HTMLText that parses placeholders instead of returning the raw value.
Upload: refactor file versioning
Fix: Incorrect calculation of UploadField height (fixes #2862)
Fix: Remove superfluous iframe resize for UploadField (fixes #2863)
ENH making /dev extendable
BUG Fixing plural_name messing up singular words ending in "e" (#3251)

This would ideally be fixed with the ability to use an external library
like gettext, but that's an API change. This for now fixes the issue
where a singular like "Page" returns "Pags" for the plural name.
BUG Fix issue with inheritance of Injector service configuration
Copy SSViewer rewrite_hash_links regexp to SSTemplateParser
As this is meant to represent the same functionality in two different
areas, it should behave the same way in both.
Updated en/topics/testing/index.md for clearer PHPUnit installation instructions

Step by step Composer installation instructions, including a composer.json example.

In addition:
- Removed self-page reference to an introduction
- Removed reference to PEAR installation instructions due to end of life
- Removed reference to Ruby as doesn't add value
- Shortened testing via Web Browser section (as covered in Composer installation instructions)
Updated html field to support quotes
Describe adding PHPUnit as a simple one line command

- Removed the composer.json example
- Removed comment about PHPUnit versions

Signed-off-by: AntonyThorpe <antony.thorpe@budget12.com>
Fixes a bug that ignored any overridden path for assets/error-404.html etc
Merge pull request #3489 from markguinn/patch-error-path

Fixes a bug that ignored any overridden path for assets/error-404.html (etc)
Update searchcontext.md with &hellip; showing ???
Merge pull request #3492 from nhorstmeier/patch-2

Update searchcontext.md &hellip; showing ???
Updated for PHPUnit version clarification

Updated Composer command to reference latest stable version as advised
Removed testing installation via Browser step
Added a note about the PHPUnit 3.7 requirement for running tests via the Browser
MINOR: Fixed copyright year
Merge pull request #3402 from halkyon/plural_fix

BUG Fixing plural_name messing up singular words ending in "e" (#3251)
MINOR: Docs: Invalid link to WAMP page
Merge pull request #3498 from edlinklater/patch-1

MINOR: Docs: Invalid link to WAMP page