fix position select2 fixing the problem that the select 2 collapse of
input field.
fix dropdown for the filters UX
Merge branch 'master' of github.com:molgenis/molgenis into feature/simplified_filter_UX_2649
add comments
change name xrefsearch to xrefmrefsearch
Change the name of the jquery.molgenis.xrefsearch.js to
jquery.molgenis.xrefmrefsearch.js

For xrefs we use the mrefcontrol without the "+" and without the AND/OR,
but with an "or" label
fix style filters
cleaning code filters
1. added consistent style to the filters 
2. added complex filter operator where the user can chose for (and/or)
3. added mini style to complex filter operator select button.
4. added label to xref always or.
add correct remove first element
Merge pull request #1683 from bartcharbon/master

add configurable maximum file size + fix no results message catalog tree
* Remove elements complex filters by clicking on remove button
* Complex functionality working correctly
* select2x2 not found fix
Merge branch 'master' of github.com:molgenis/molgenis into feature/simplified_filter_UX_2649
Some code cleaning actions
Fix
Merge pull request #1681 from jjettenn/feature/simplified_filter_UX_2649

Feature/simplified filter ux 2649 W.I.P
MREF control with AND/OR dropdown front of de select2 and '+' and '-'
after
use "mini" class to create smaller buttons
no AND/OR button for range/data/int, add a "or" label
Added handlebars to core-ui and started using it in disease matcher
fixed adding handlebars