Implements Kahan's versions of elementary complex functions…

…paying particular attention to behavior near branch cuts.

Functions: sqrt, ^, log, asin, acos, atan, tanh, asinh, acosh, atanh
Includes also the ssqs to compute the mod-squared of a complex number scaled by a power of 2 to avoid overflow/underflow
Issues
- The ^ function fails tests so is disabled for now.
- The log function works only for `Complex{FloatingPoint}`. Explicitly casting `{T<:Integer}Complex{T}` to floating-point `Complex` causes tests to fail.

Ref: [Branch cuts for complex elementary functions](http://people.freebsd.org/~das/kahan86branch.pdf)
Correctly detects for both underflow and overflow in ssqs
Fixes type error in log
Corrects underflow check
Adds edge cases for all except atanh, atan
Reorders tests
Add Broadcast module with staged broadcast operations
allow any Range in @parallel. fixes #3096
fix #3126, syntax error for ... in the middle of arg list
Added trsv and trsv! to Base.LinAlg.BLAS namespace

Plus cosmetic changes to indentation and creating more informative error messages.
improve hypot() for #3101
make deserialize() more robust against undefined functions
Added doc/DocCheck.jl: functions for checking documentation

* undefined_exports(m::Module): list the undefined exportss in a module
* undocumented(), undocumented_by_file(), undocumented_rst(): produce a list of undocumented methods in various formats
* isdeprecated(fn): true if fn is deprecated

Additional functions in base:
* current_module(): return the current module
* functionlocs(fn): return all function locations; (functionloc(fn) returns just the first)

Also:
* commented out undefined functions in exports.jl (these could probably be removed)
Merge pull request #3130 from JuliaLang/db/trsv

Added trsv and trsv! to Base.LinAlg.BLAS namespace
Merge pull request #3129 from mlubin/master

Updates for parallel docs
Merge pull request #3120 from kmsquire/undoc

RFC: Added doc/DocCheck.jl: functions for checking documentation status
add missing export of gradient()
disallow subtypes of ...
insert some conversions to make custom Integer types more likely to
work with indexing. fixes #3106
Some fixes to the Gedit configuration file
Added subtypes functions, updated help, docs

* Added subtypes(T), subtypetree(T)
* Updated help(x::DataType) to print super, subtype info
* Doc fixes/updates.
Merge pull request #3135 from waldir/master

Some fixes to the Gedit configuration file
Metaprogramming doc update (minor).