* Added IdentityAlways and IdentityByDefault as value generation
  strategies alongside Serial. Serial is still the default to
  maintain backwards compatibility.
* Scaffolding is supported
* Migrations are supported, including changing from one identity
  strategy to another (always->default) and from serial to
  identity.

* Bring back proper handling of dropped columns
* Correctly detect serial columns again

int, integer and int4 all need to point to the same mapping.

https://github.com/aspnet/EntityFrameworkCore/pull/10990

Disable appdomains in xunit

(cherry picked from commit 2fa4a0b7)

After https://github.com/aspnet/EntityFrameworkCore/issues/10796 was
fixed.

Bump version and switch nuget feed

* Install hstore on PostgreSQL
* Upgrade to PostgreSQL 10.1 on Appveyor, no Travis support for 10 :(

PostgreSQL 10 allows sequences to be int2 or int4.

Closes #301

* Changed to new 2.1 scaffolding test structure
* Added support for scaffolding partial indexes
* Date/time type precision is now scaffolded
* Scaffolding type modifier (precision/scale) is now done database-
  side, much simpler.
* Fixes start/min/max scaffolding for non-bigint sequences.
* Various fixes and refactoring in NpgsqlDatabaseModelFactory

Closes #297

* Moved to new 2.1 type mapper interface
* Switched to simple hardcoded mapping creation rather than attempting
  to dynamically load them from ADO, which made no sense as we need
  literal generation anyway.
* Added many mappings with the literal translations, not complete.

* Float dependencies for EF Core components
* Npgsql 3.2.6

Incomplete

Fixes #278

Fixes #267

Since server would store underlying type of enum hence server eval causes incorrect result

See https://github.com/aspnet/EntityFrameworkCore/issues/9894

Fixes #264