OPAL-2128: Filter improvements. Categorical dropdown implemented
OPAL-2128: Numerical dropdown implemented
OPAL-2128: Default, date time criterion implemented
OPAL-2118: Keep filters when switching tabs
OPAL-2118: Keep filters when switching tabs
OPAL-2118: Code inspection
Merge pull request #354 from emorency/feature/OPAL-2118-Values-filter

OPAL-2118: Values filter improvements and keep filters when switching tabs
OPAL-2118: Fixed PMD warnings
Merge pull request #355 from emorency/feature/OPAL-2118-Values-filter

OPAL-2118: Fixed PMD warnings