Add top-level CMakeLists.txt, configure script and Makefile

[meyerj]

Follow-up of #13. Partially addresses #27, #30, #32, ...

Obvously we also have to update the website http://www.orocos.org/, because lots of information found there is actually outdated.

Instead of a complex and hard to maintain shell script (#13) I propose to use CMake's powerful ExternalProject module to build and install the individual subprojects in their own build directories in the correct dependency order.

AutoProj never really worked for me, partially because it depended on newer Ruby versions than the ones available with Ubuntu LTS releases. But I have to admit that I have not tried recently. A pure CMake approach seems to be more appropriate for most users. Installation of dependencies is left to the user (still needs more detailed documentation). But of course I am open to also add or link instructions on how to optionally build the toolchain with AutoProj.

By default the current CMake config tries to checkout the branches with the same name as the current branch in the orocos_toolchain repo. This can be overwritten by adding -DGIT_TAG=<branch or tag> to the configure script or directly to cmake.

For non-ROS users the patch also requires #33 because the current version of orocos_toolchain/CMakeLists.txt depends on catkin and configuration fails if catkin cannot be found in the CMAKE_PREFIX_PATH. ROS users would probably build and install with catkin_make_isolated or catkin_tools instead, so the new top-level CMake config and scripts are of limited use.