Don't treat null values as zero for graduated symbology
Use isEmpty() to test for null values
Use isNull() to test for null attribute values
30c7ec40 also applies to mingw
Fix #7195, transparency options in composer should be 0-100%
Merge pull request #453 from nyalldawson/gradfixes

Don't treat null values as zero for graduated symbology (Fix #6096)
Allow long/bigint columns to be used for graduated symbology (#4593)
Merge pull request #457 from nyalldawson/gradfixes

Allow long/bigint columns to be used for graduated symbology (Fix #4593)
Merge pull request #458 from 3nids/respectUIimmutableoption

respect the disabled option defined in the UI file