Add libunwind patch from Pyston
beginswith, endswith accept Chars
more efficient setindex for sparsematrix
replaced splice! with deleteat!
Expand macro documentation

These changes are based somewhat on the [discussion on the julia-users list](https://groups.google.com/d/msg/julia-users/YTZM3Biy-rM/m0orpSjQ8RIJ) and somewhat on my own stumbling points as I was learning how macros worked.

Here's the motivation behind these changes:

* Stress that macros *return* an expression to be evaluated, and hopefully make it look like they're less magical to newcomers. Make `return` explicit in the examples, so it looks less like textual substitution and more like a mapping from exprs to an expr.
* Provide an example where the macro is more than just return an expression. The changes to `@assert` since the original documentation was written make this very natural without needing to contrive another example.
* Use function such as `macroexpand` and `dump` in the examples to help make things more concrete and give users tools to play with.
* Make the hygiene section introduction a bit more clear, with an emphasis that the only thing it needs to worry about is the returned expression.

I think this should help folks 'get' macros a bit quicker. I hope.
Update linalg.rst

Complemented linreg() documentation
Disable the dnsimp test of ARPACK also, as it is not built anymore.
Loosen types on mmap on unix

In particular make it work for isa(fd,RawFD) and offset any integer type (there is a lot of precedent for allowing any Integer Rather than just FileOffset. In particular most of the io.jl methods do this).
Merge branch 'master' of github.com:JuliaLang/julia
Merge pull request #6789 from tanmaykm/sparse

more efficient setindex for sparsematrix
Change get-arpack target to match new filename
Merge remote-tracking branch 'origin/kf/mmap'
Make RawFD a noop for passed in RawFD

this can happen in the Windows mmap code and it would be much nicer if it
just worked.
parse sqrt symbol (√) as a unary operator
Fix clean-arpack as well
Revert "Manual update"

This reverts commit a8dbe6bd5219285681870a530d4f449f89b7b6c8.
Changed .julia -> .julia/v0.3
Merge pull request #6806 from JuliaLang/kms/fix_docs

Fix #6575
Corrected examples on linreg function

Removed the prompt and semicolons
Fix promotion for generic inverse. Add convert methods for Triangular.