Replace HTML entities in GridFieldAddExistingAutocompleter->doSearch() with actual charaters as the DropDown does not play nicely with HTML entities
disable source_file_comments in GridFieldAddExistingAutocompleter->doSearch() because they would be displayed as plaintext in the dropdown
Add X-Backurl header to CMS ajax requests
Merge pull request #2657 from kinglozzer/cms-xhr-referer

NEW: Add X-Backurl header to CMS AJAX requests
Fix installer isIIS() to include IIS versions greater than 7.
Merge pull request #2672 from tiaitsch85/tiaitsch85-patch-1
API: Implement SS_Map::push() to append values.

FIX: SS_Map::count() not taking into account additional firstItems
FIX text/html type for Debug::friendlyError() in live mode

Avoid unparsed HTML responses in case of httpError(4xx) or
httpError(5xx) in live mode. The SS_HTTPResponse_Exception constructor
automatically set "text/plain" a content type, which conflicts
with the later choice of Debug::friendlyError() to return HTML.

This is a hotfix, needs more work to properly separate
logic flow from presentation concerns (e.g. through request processors).
Merge pull request #2671 from wilr/ssmapfixes

API: Implement SS_Map::push() to append values.
Merge pull request #2674 from chillu/pulls/friendlyerror-contenttype

FIX text/html type for Debug::friendlyError() in live mode
Update server-requirements.md

Typo fix
Merge pull request #2675 from martinduparc/patch-1

Update server-requirements.md
Merge pull request #2650 from Zauberfisch/GridFieldAddExistingAutocompleter

Implove GridFieldAddExistingAutocompleter->doSearch() html output
added filterByCallback() to interface SS_Filterable and all implementing classes
Merge pull request #2626 from Zauberfisch/filterByCallback

filterByCallback added to SS_Filterable interface and implemented in ArrayList