FIX Only block root vendor folder

Use RewriteRule instead to take in account any subfolder via RewriteBase. Deny ss-cache and composer via RewriteRule too.
BUG GridFieldFilterHeader works without non-filterable cols

Previously relied on the presence of a last column which wasn't filterable,
commonly a GridFieldEditButton. If this wasn't present, the filter buttons
were never added, leading to the GridField JS reload request being sent
without the required button form action, so GridFieldFilterHeader->handleAction()
was never called.
Update server-requirements.md
Update common-problems.md
Update common-problems.md
Update common-problems.md
Merge pull request #1982 from chillu/pulls/gridfield-filter-cols

BUG GridFieldFilterHeader works without non-filterable cols
Merge pull request #1786 from colymba/3.0-htaccess-fix

vendor folder is blocked only if outside themes
API UploadField functions on new records

Fixed regression from 1e5d40474d43ddb0ade22bbf7db5ec494b979fea (UploadField::canPreviewFolder).
Merged in pull request #2009 - (6018bdd631ec98345bba5cd26ef5a29f6f412678).
Merged pull request #1259 (34bfc862eee061ce30998a085aac6170022c3a7e).
Fixed scrutiniser issues
BUG Fixed major issue with testing dataobjects that implement TestOnly and extend non-TestOnly dataobjects. Database regeneration would incorrectly populate the ClassName column
BUG: correct handling of multiple classes
Fixes for LeftAndMain::require_themed_css()

LeftAndMain::require_themed_css() was setting an incorrect property, and a typo meant that those requirements would never be detected anyway
FIX Making path names consistent

I've changed the variables to use the absolute path as the path is unhelpful for debugging and this is more consistent with the other lines of code below
Merge pull request #2024 from kinglozzer/leftandmain-themedcss-fix

Fixes for LeftAndMain::require_themed_css()
Merge pull request #2025 from dhensby/patch-1

FIX Making path names consistent
Merge pull request #2023 from g4b0/left-and-main-classes

BUG: correct handling of multiple classes
Merge branch '3.1-uploadfield-enhancement' of git://github.com/tractorcow/sapphire into tractorcow-3.1-uploadfield-enhancement
Fixed UploadField width (same as textual fields)

Was getting too wide due to padding which isn't applied
to other fields (e.g. TextField)
Merge pull request #2017 from tractorcow/3.1-classname-test-fix

BUG Fixed major issue with testing dataobjects that implement TestOnly