DbObjectExecutionFixture cleanup

- extract column heading as class
- remove all null checks (cannot really understand when those conditions occur)
- separating fit parts from dbfit parts
Execute fixture no longer extends DbObjectExecutionFixture
better separation of DB and FitNesse parts in SymbolAccessQueryBinding
extract CellTest, ContentOfTableCell, TestResultHander
reduce visibility of DbParameterAccessor methods
DbParameterAccessor => ParameterOrColumn
move exception expectation methods to ExecuteProcedure
extract setting input params as method in DbObjectExecutionFixture
cleanup in ExecuteProcedure
better variable names in DbStoredProcedure
call more appropriate method in fit.TypeAdapter
moved responsibilities out of ParseHelper
reduce duplication, fix formatting in CellTest
SymbolUtil#getValueOfSymbol => SymbolUtil#getSymbol
WIP: DbObjectExecutionFixture doesnt use Bindings
better naming