Revert "Split arel_table into method to get a relation and another to memoize the default relation."

This reverts commit bd517908.

naming. Use bang methods convention in methods that alter the
relation.

options[:group] is given.

Signed-off-by: NPratik Naik <pratiknaik@gmail.com>

PostreSQL.

associations.

Signed-off-by: NMichael Koziarski <michael@koziarski.com>
[#1229 state:committed]

Signed-off-by: NMichael Koziarski <michael@koziarski.com>
[#1229 state:committed]

Break up DependencyModule's dual function of providing a "depend_on" DSL and "included" block DSL into separate modules. But, unify both approaches under AS::Concern.

Calculations now use construct_calculation_arel, making construct_finder_arel less hackish.

Updated ARel to support PostgreSQL.

Refactor to use arel_table method, and also use the same method name for instance and class methods.

Implemented other methods in AR::Base with Arel support.

Signed-off-by: NPratik Naik <pratiknaik@gmail.com>

Signed-off-by: NPratik Naik <pratiknaik@gmail.com>

Make sure any Fixnum returned by a DB sum is type cast to a Float before standard converstion to a BigDecimal [#8994 state:resolved]
Signed-off-by: NJoshua Peek <josh@joshpeek.com>

If average value from DB is 0, make sure to convert it to a 0.0 float before calling #to_d on it [#1346 state:resolved]
Signed-off-by: NJoshua Peek <josh@joshpeek.com>

Model.sum delegates typecasting to the column being summed. If that's not feasible, returns a string.
Model.avg always returns big decimal.