Clarifying build dependencies for Linux

[Thav]

On Ubuntu 10.10 I installed the following packages through apt-get to get the build running:
libsdl1.2-dev
ftgl-dev

Presumably I was in good shape for already having install build-essential a while back. libsdl pulled a few things in with it, so I'm not sure if I grabbed too much. On first make attempt I didn't have the OpenGL dependency, but after installing the two packages listed above I apparently had it.