DDC-1813: Save column types in ClassMetadataInfo#columnTypes array instead of ClassMetadataInfo#fieldMappings['type']

[doctrinebot]

Jira issue originally created by user rivaros:

Because you save column types in fieldmappings only, type information is not saved for join columns.

Not having type info for join columns, makes it impossible to do call 'convertToPhpValue' on join columns.

For example see a demo of problem here:
#347

[malukenho]

@Ocramius should we move it do 3.x if still valid?

[Ocramius]

This is already done internally now, but indeed ORM 3 will have type info for all columns, including join columns.

Closing here.