Windows: Don't test ispath on deleted file or dir

These are failing with "stat: operation not permitted (EPERM)". There may still be
file handles open so the unlinked file and removed directory cannot be stat-ed.
linrange for constructing ranges by endpoints and length
linrange length check, add tests
linrange type consistency
Clean up examples/. Add test/examples.jl to track breakage for examples. Fixes #7332.
Added mark/unmark/reset/ismarked to IOStream, IOBuffer, and AsyncStream
Also added show() for IOBuffer.

* Define mark, reset, unmark, ismarked for IO only.
  This is slightly sketchy, as it assumes that IO.mark exists, but
  is perhaps better than duplicating the code for all subtypes.
Fix rare and unlikely early free

During bootsrap, some code called the generic "map"
triggering compilation of the inference code in
jl_apply_generic -> jl_mt_assoc_by_type ->
cache_method. This particular map method gets
overwritten in the process and by the time
jl_apply_generic gets its function pointer back, it
is not present in the method table anymore.
Then, in jl_trampoline, compilation allocates some
managed memory, sometimes triggering GC, thus
sometimes freeing the function object before it is
called.
fix missing root on module allocation
Remove UNDOCUMENTED.rst from docs
Add lyap() and sylvester().
Test for lyap() and sylvester()
and taking some tests out of the inner loop in linalg1.jl
Fix: Scale is real
Doc for lyap() and sylvester().
Avoid explicit transposes
Merge pull request #6627 from simonbyrne/linrange

`linrange` for constructing ranges by endpoints and length
Allow using system dSFMT

Add USE_SYSTEM_DSFMT variable. Rename librandom to
dSFMT since distributions call it that way.
add option to use mmap in gc, and to free pages later. ref #7381

also fix gc time printing code
allocate symbols in their own pool, since they are never freed

this helps reduce heap fragmentation a bit
Merge branch 'master' of github.com:JuliaLang/julia
Merge pull request #7448 from nalimilan/librandom

Allow using system dSFMT