Closes #2436

fixes #2270

While technically it could work, the schema introspection of Sqlite
platform has severe flaws preventing us to provide reliable support
of partial (and non-partial) indexes for the moment.

Support for Partial Indexes was available in Doctrine 1 following
http://www.doctrine-project.org/jira/browse/DC-82. This commit
reintroduce support for Doctrine 2. We use the same syntax with an
optionnal "where" attribute for Index and UniqueConstraint.

See symfony/symfony#10238

This reverts commit 5a46f577.

- 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

Fix creating indexes for renamed columns and updating foreign keys for renamed parent tables in SqlitePlatform

Changed default flags (create indexes and create foreign keys) in SqlitePlatform::getCreateTableSQL method