Framework parallel tests, stage q: LevelOfParallelismAttribute, ParallelizableAttribute, separate queues for parallelizable and non-parallelizable fixtures in either an MTA or the STA, use WorkShifts to organize work into different groups that can be run during the same time period, add tests for various attributes, fix build for all supported runtimes
Fix text alignment and add some forgotten tests to a few projects
Merge pull request #97 from nunit/parallel-attribute

Framework parallel tests, stage 1