Numeric column type

[ViliamKopecky]

• With configurable precision and scale (def.numericColumn(20, 2)).
• Transported as string ('-123456789123.456').
  • Currently postgres sends trailing 0 filling the precision (123.450000000) - maybe Contember might transport shorter variant (123.45), or maybe make this behavior configurable.
• Default might match JavaScript Number precision (I believe that would be (17, 15)). Not sure.
• Filter as numbers (gt, lt, …). Currently works as expected.
• Order as numbers. Currently works as expected.