Fix compatibility with TYPO3 6.1
refactored the MigrateTask to prevent OutOfMemory errors on
large data sets.
Fixed breaking MigrateTask on missing files exception.
Added Migrate task to convert DAM selections to sys_file_collections
ADD: new task for migrating dam categories to new typo3 categories
CHG: new db field for origin dam_cat uid in sys_category, check if set parent uid is availablle
ADD: new migration task to link the migrated categories to the migrated files
Merge pull request #1 from alex-boehm/master

Merge with most advanced branch available