3.3.0

This major release adds bug fixes and a minor feature, specifically:

• toil clean is more robust and can clean partially corrupt job stores (#869 et al)
• job.fileStore.writeGlobalFIle(…) returns a magic string with a .size attribute reflecting the size of the file just having been written. In conjunction with promised requirements, this small change greatly simplifies dynamic computation of job requirements as a function of the size of another job's output (#1014)
• Two race conditions in the caching layer are fixed (#1046 and #1033)
• A show-stopping race condition with promised requirements was fixed (#1039)
• Several other bug fixes and code quality improvements
• The undocumented cache= job requirement has been removed