fix rst markup in doc/manual/types.rst

In rst markup, inline literals (i.e. code samples)
can't be nested inside strong emphasis (bold).
The backticks were showing in the rendered output.
Minor tweaks to doc/manual/variables-and-scoping.rst
A few small adjustments in the manual
make sure dimensions match in complex(). fixes #3090
Shut down all named pipes and tcp streams in jl_close_uv.
Add a test for shutdown being called twice.  Unfortunately it hangs rather than fails.
Stop using libuv's flags, check in jl_close_uv if close has already been called from julia
Change is_open to isopen
Test handle type before testing writable
If a shutdownable stream is not writable, don't call uv_close on it.
Get jl_uv_close working again by checking uv_is_closing at the top and closing when a handle isn't writable or closing
Use JULIA_CB to cache isopen
pkg2 wip: terse show for Requires and Available without .requires
pkg2 wip: calculation of dependencies, stripped of fixed packages.
Add gglse! for equality-constrained least squares
Additional dimension checks
added isela function, removed redundant functions: isinteger, isreal, iscomplex, isbool.
renamed integer_valued, real_valued, float64_valued
rename isinteger/realvalued -> isinteger/real, isela -> iseltype
add array methods for isinteger, isreal, isfloat64
missing methods for isfloat64