doc: edits to the FAQ entry on why we use machine integer arithmetic.
doc: slight FAQ edit.
doc: a couple more edits to the FAQ entry on integer arithmetic.
doc: FAQ copy fixes.
Merge pull request #4726 from JuliaLang/teh/sprand

WIP: Avoid duplicates in sprand
fix #4917, better checking of module syntax objects
fix #4919, macroexpander bug in "using" etc.
Make sqrtm work for vectors
DOC: Added section about column-major arrays to perf tips

Also added a note to the noteworthy differences from Python section
Merge branch 'master' into arrOrderPerf
Merge pull request #4897 from JuliaLang/mn/doctest

close #52 (run doc example code as a test suite)
remove trailing newline from show(::SparseMatrixCSC)
Disallow the fish shell; default to /bin/sh if not overriden.

Also Add in a warning notice when auto-changing the user's shell
Merge pull request #4924 from staticfloat/lutefisk

Disallow the fish shell; default to /bin/sh if not overriden.
DOC: Code/timings now appear in same order

Also removed "Remember" from section title

Also added link in arrays section
DOC: Changed title of column-major perf tip section

Restored the "remember" that was there to match
imperative nature of other titles
Merge pull request #4921 from spencerlyon2/arrOrderPerf

DOC: Added section about column-major arrays to perf tips
Pkg.GitHub: if GitHub user isn't configured, give a clear error.
Pkg.GitHub: some `which`es don't support `-s` and it's unnecessary.
doctest: make sure julia-basic is in PATH