Improve type validation

[epoberezkin]

Problem

1. Duplicate validation of type for type integer.
2. If there is no type-specific keyword for (one of) required type(s), these types are validated after all keywords.

Both inefficiencies prevent implementing ajv-keywords #100: errorMessage keyword does not catch type errors when type is validated after all keywords.

Solution

1. Schema {type: 'integer', minimum: 1, maximum: 5} is currently compiled to:

if data is a number, check that it is >= 1 and <=5, otherwise check that it is an integer.

Instead it should be compiled to:

if data is an integer, check that it is >= 1 and <=5, otherwise fail validation.

2. Validate all types for which there are no keywords before all keywords.

[epoberezkin]

change for integer is reverted so that schema {type: 'integer', maximum: 5} returns 2 errors for 5.5.