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
add 3.1.6 docs
Merge remote-tracking branch 'origin/3.1.6' into 3.1
Minor correction to documentation
FIX: Sorting a DataQuery over a relation.

When sorting a DataQuery over a relation, the SQLQuery automatically included the sort column. The issue with the implement is that potentially the joined record has a field with the same name as the source record causing it to be overridden.

In the attached test case, without the patch the title will be set to 'Bar' rather than 'Foo'.

This patch aliases the sort column. Alternativally a patch would be to
Merge pull request #3436 from dnadesign/fixsortonrelations

FIX: Sorting a DataQuery over a relation.
Fix deprecation warnings in internal SQLQuery usage
Merge pull request #3449 from camspiers/patch-2

Fix deprecation warnings in internal SQLQuery usage
RSS feed should be sent with charset=utf-8 header
Merge pull request #3453 from uniun/patch-1

RSS feed should be sent with charset=utf-8 header
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.
BUG MySQLDatabase performs queries on wrong DB connection when using connection $name != 'default'
Merge pull request #3465 from tractorcow/pulls/3.1/fix-query

BUG MySQLDatabase performs queries on wrong DB connection when using connection $name != default
showqueries output incorrectly shows "ms" instead of "s"