tests: Avoid compiler warnings
gnulinux: Fix signedness compiler warning
tests: Remove unused variable warning in mqueue archive test
tests: Remove unused variable warning in property composition test
tests: Add tests for FileDescriptorActivity
time: Support Second conversions to/from micro- and milliseconds
logger: Support logging using log4cpp framework

Supports logging using the log4cpp framework, which replaces logging
both to file and via printf. The log4cpp option defaults off. This
fix also ensures that application code is informed of the build option.
Merge branch 'fixes' of git://gitorious.org/orocos-toolchain/snrkiwi-rtt into toolchain-2.7
cmake: generate typegen typekit in build dir instead of src dir

Signed-off-by: Ruben Smits <ruben.smits@intermodalics.eu>