Updated info in README.md

* CentOS 5 building with gcc44
* Ubuntu PPAs
* Troubleshooting table
* Removed Rmath reference
fix #3672, dispatch bug due to type intersection

the improved typeintersect revealed a bunch of ambiguity warnings,
which could be fixed up by improving method specificity a bit, and
manually patching one case.
Manually symlink libopenblas.so to libopenblas.so.0 in usr/lib/
Merge pull request #3681 from staticfloat/arpacklinkfix

Manually symlink libopenblas.so to libopenblas.so.0 in usr/lib/
Update OS X build instructions in README.
Return sum of squared residuals from gglse
Fixes ssh tunnel command setup. Also fixes #3671
Merge pull request #3555 from JuliaLang/anj/gglse

Return sum of squared residuals from gglse
sorting: make `order` and `alg` keyword arguments.

The idea here is that the ordering and algorithm for sorting are
two orthogonal parameters that have sensible defaults: neither,
both or either can be independently specified. The resulting API
is slightly more verbose but also somewhat more self-documenting.

Another sign that this might be on the right track is that this
change reduces the LOC of base/sort.jl by 41 lines and reduces the
method count of sort, for example, from 12 to 6.
sorting: move matrix sorts up with other generic sorting functions.
sorting: eliminate a few nans2{left,right} definitions via defaults.
sorting: keyword arguments for `by` and `lt` as well.
document SymTridiagonal, improve other tridiagonal docs
sorting: make ReverseOrder parametric -- can reverse any ordering.
more helpful error messages in ccall and cglobal
cleanup UV objects, especially status codes. fixes #1923. fixes #3676
on uv close, notify all waiting tasks
fix @assert for use during sysimg build, and use it
fix #3544
fix small TODO in quadgk (use SymTridiagonal eigensolver)