Added the 'mydebug' configuration to 'engrid.pri', so that debug symbols can be built into the binaries.
Added the 'mydebug' configuration to 'libengrid.pro'.
Added the 'mydebug' configuration to 'engrid.pro.app', as well as separating the inclusion of library dependencies, because BRLCAD (at least on Ubuntu 12.04), needed a hack of pre-linking to 'libz.so' before BRLCAD's 'librt.so'.