rtt: removed corba stuff from package.xml
working on re-adding rosbuild support for downstream packages
rtt: also respect LIBRARY_OUTPUT_PATH cmake variable in UseOROCOS-RTT.cmake as many rosbuild-style packages use it
rtt: search for a rosbuild package in orocos_use_package() and recurse
Merge branch 'catkin' into rosbuild_support
Merge pull request #3 from meyerj/rosbuild_support

Pulling in Johannes's Rosbuild support
re-adding old manifest.xml
rosbuild + catkin client support

- restoring old rosbuild support
- checking manifest parsing back from package.xml
- updating rosbuild check to use ROSBUILD_init_called
- adding catkin-supporting pkg-config file generation
Removing unnecessary addition to pkg-config path since orocos won't be built in a rosbuild tree any more
changing orocos_package to ORO_ROSBUILD_PACKAGE_NAME because that's where it's actually used
Fixing rosbuild/catkin cache variable
pkg-config generation for install/rosbuild/catkin

- add pkg-config generation for catkin
- remove duplicate pkg-config file source
- replace "@" with "\@" in pkg-config file template to prevent
  substitution in string as per
  http://www.cmake.org/pipermail/cmake/2006-January/007936.html
Splitting orocos_use_package into use & find, adding more catkin support
pkg-config generation missing @ escapes
don't auto-link catkin by default
fixed LIBRARY_OUTPUT_DIRECTORY for components, plugins and typekits if ORO_USE_ROSBUILD is set
fixed include_directories in orocos_use_package()
fixed parsing of xpath output in orocos_get_catkin_deps() cmake function
Fixed spaces in Requires: list in generated pkg-config files

string(CONFIGURE ...) concatenates all elements of list variables without spaces. Example:
Requires: orocos-rtt-gnulinux rtt_rosnodertt_sensor_msgsrtt_geometry_msgsrtt_nav_msgs
useorocos: set ${PACKAGE}_FOUND variable to true if the package has been found in orocos_find_package()

This follows cmake standards for similar commands like find_package().
Also added a FOUND check to orocos_use_package() although it's not really required here.