Minor code tweaks and test cleanup

[djlambert]

A number of miscellaneous changes:

• Changed a few comparisons to strict type checking.
• Replaced switch block in AbstractGeometry::validateRingValue() with if.
• Add result cache to tests.
• Fix incorrect tests namespaces.
• Remove old test init code necessary for importing doctrine test case, add test namespace to composer.json, and update phpunit config to use composer autoload.
• Add tests for LineString geography.