query: search func/prop name by lower case name

this enables to use like isDirectMessage/isDirectmessage/isDIRECTMESSAGE
  property name.

This already supported in StandardPropertyFactory while QueryCompiler didn't support
  with LowerCaseName, so we could't use LowerCaseName
FilterEditFrame: Fix NPE if closing frame with empty query statement
query: rename ambiguous "filter" to "query"
QueryCompiler: fix filter function doesn't search with LowerCaseName

More user-friendly error message if function is not found