Defines +,- for Triangular matrices

Fix #5927
run pkg test on travis
Add `-T` -a` to the default ssh command/s.

- Disable TTY allocation
- Disable agent forwarding
Disable x and clear all forwardings by default as well.
New version of mingw64-libexpat
Merge pull request #7627 from ronisbr/master

New version of mingw64-libexpat
Quick fix to metaprogramming.rst
Merge pull request #7629 from kersulis/patch-1

Quick fixes to metaprogramming.rst
parse ¬ (\neg) as a prefix operator
Merge pull request #7630 from stevengj/neg

parse ¬ (\neg) as a prefix operator
Add a brief explanation of n:n-1 as an index

Update splice! docs to describe insertion without removal of any elements.
Merge pull request #7631 from JuliaLang/kms/doc_empty_range_as_index

Add a brief explanation of n:n-1 as an index
Don't be so picky about patchelf version, as there are now newer versions floating around
Fix type inference for \
Bump patchelf to 0.8
Whoops, forgot to remove bootstrap line, thanks @tkelman
add some precompile items to help Pkg.update speed
In Makefiles, use $(shell which ...) not $(which ...)
call update_all_fptrs earlier, to avoid some redundant compilation
Change code_lowered to take Callable instead of Function. Fixes #7636.