#2794 allowing `DateTimeImmutable` instances when converting in mutable date types - reverts unintentional BC break

Add conversion exception when date and time type convertToDatabaseValue methods are passed non-null values that are not DateTime instances.

TimeType resets date fields (i.e. unused DateTime object fields) to UNIX
epoch (1970-01-01). This makes TIME field mapping stabe (i.e. same time
will be always mapped to the same DateTime fields).

See DDC-179 (similar issue with DateType). Fixes DBAL-993.

- Fixed docblocks
- Removed return statements on void methods
- Cleaned up unused private / local variables
- Fixed license issues
- Removed SVN leftovers
- Fixed doctrine-project.org links
- Added line breaks before return statements

DBAL-26 - Fix nasty bug with null values in Date, DateTime, DateTimeTz and Time fields introduced with the DBAL-22 fix

DBAL-22 - Throw ConversionException if DateTime, Time, Date, DateTimeTz, Array or Object conversions from the Database to PHP fail

[2.0][DDC-354][DDC-425] Fixed. Encapsulated SQL logging better in the DBAL. Added binding types to DBAL mapping types as well as using these binding types in the persisters. Query and NativeQuery now support PDO binding types as well as DBAL mapping types when binding parameters.

[2.0][DDC-92] Fixed. Patch provided by Christian Heinrich. [DDC-274] Started some method renaming. [DDC-142] Fixed (join column names and discriminator column names dont support quoting) [DDC-258] Fixed.

[2.0][DDC-30] Fixed null values with Date, Time and DateTime types. Thanks Ismo for report and patch

[2.0] Streamlined result structures. Hydration improvements: Small overall improvements, large improvement for (joined) fetched collections (~60%). 

[2.0] Implemented DQL bulk DELETE support for Class Table Inheritance. Other cleanups, refactorings and docblock additions.