Fix an exception when parsing a multi-line command that ends in cd
https://github.com/fish-shell/fish-shell/issues/511
exec.cpp:exec: Don't remove block_io elements from j->io

When dulicate_prepend prepend copies of block_io elements to j->io, the
removing simply does nothing. Now that the same pointers are prepended to
j->io, don't remove them.
Revert "Revert shared_ptr<io_data_t> changes until kinks are ironed out"

This reverts commit 77f1b1f0fe27778750bb9b9aa53f6bc42d5e5843.
Make do_builtin_io multi-fork safe, moved it to postfork.cpp
Addresses https://github.com/fish-shell/fish-shell/issues/495
use debug_safe in postfork do_builtin_io. Closes #495
Fix for issue where completing in the middle of a command may append extra junk at the end of the completions in the list
https://github.com/fish-shell/fish-shell/issues/301
Don't call expand_home_directory from within parser_t::test - it may hang
https://github.com/fish-shell/fish-shell/issues/512
Formatting
Added a seq function that defers to the seq command if present
https://github.com/fish-shell/fish-shell/issues/137
Remove seq.in, in favor of the new function. Remove seq detection from configure.ac. Teach the Makefile how to remove old installed seqs.
Actually add the seq function (oops)
Make umask work on OS X
https://github.com/fish-shell/fish-shell/issues/515
stop profile switch from crashing (issue #517); also make print_profile use a loop instead of recursion
fix a memory leak in profiling, add a profiling test
Fix for missing first character in completions
Fix proc and pid completion on OS X, and improve it on Linux.
https://github.com/fish-shell/fish-shell/pull/129
Ajax fix for Firefox, it isn't XML.
Formatting
add a JOIN_THREADS_BEFORE_FORK preprocessor flag to help debug locking problems