Clarification what 'atomic' means here.

Signed-off-by: Edward Z. Yang <ezyang@mit.edu>
Add setEnv/unsetEnv to System.Environment; fixes #7427

Patch from Simon Hengel.
Fix a comment
Update GHC.ForeignPtr to use addCFinalizerToWeak#
Fix hClose002 with the threaded RTS IO manager

If 'close fd' failed, then the MVars in the callbackTables would be
left empty, which caused deadlocks when we tried to 'take' them again.

Now we use 'finally' to ensure that they are refilled even if 'close'
throws an exception.
Fix hSetBuffering004 to work with dynamic ghci

We need to actually consume the rest of stdin, or ghci will try
to interpret it as commands.
Ignore editor backup files
Fix build on OS X
Catch an illegal pragma and fix a typo
fix markup bugs
Add a section of documentation about the interaction of threads and finalizers