Upgrading depenency on rake-compiler to latest 0.8.x.
Fixing a typo/bug in the windows cross-compile rbconfig-1.9.3 DLDFLAGS check.
Experimental support for cross-compiling for ruby 2.0 on windows.
Merge branch 'windows-ruby-2.0-support'
Version bump to 1.5.7.rc3, plus changelog update.
Using mini_portile to compile libxml2 and libxslt on any (non-windows) platform.
dependencies.yml is now the central location for library dependencies.

Note that this is for both windows cross-compile and packaged dependencies.
Upgrading libxml2 dependency from 2.7.7 to 2.7.8.

Affects only windows users at this time.
mini_portile is a gem dependency if we're building libxml2.
If we're building libxml2, include the tarballs in the gem manifest.
Upgrade mini_portile to support FTP, and removing my FTP-support hacks.