add new test bag: phidgets_imu_upside_down

This is from a phidgets imu, running the phidgets_imu driver mounted on
a wheeled robot that drives a small trip through an office. The IMU is
mounted upside down (i.e., the chips on the board are on the upper side,
lin_acc.z is ~ -9.81). The USB port points to the right side of the
robot. Rotation quaternion from /base_link (x pointing forward, z
pointing up) to /imu is (0, 1, 0, 0).

Contains /imu/data_raw and /imu/mag topics.
first fixes
adapted to groovy
Merge pull request #12 from lorenzoriano/groovy into groovy
Merge branch 'groovy' of https://github.com/mickeyxu/imu_tools into groovy
gyro drift correction function added in MARG implementation
Merge pull request #13 from mickeyxu/groovy

Added gyro drift correction part from Madgwick's report for the MARG implementation.
fix initialization of initial rotation

Thanks to PaulKemppi! Closes #4.
fix typo: zeta -> zeta_
add .gitignore
catkinization of imu_tools metapackage
Merge pull request #16 from kth-ros-pkg/hydro

catkinization of imu_tools metapackage
updated README to reflect catkinization
README: update link
fix implementation of invSqrt()

The old invSqrt() implementation causes the estimate to diverge under
constant input. The problem was the line `long i = (long)&y;`, where 64
bits are read from a 32 bit number. Thanks to @tomas-c for spotting this
and pointing out the solution.

Fixes #17.
Merge pull request #20 from mintar/fix_invsqrt_union_method

fix implementation of invSqrt()
install nodelet xml file

Otherwise the nodelet can't be found
Merge pull request #24 from v4hn/install-nodelet

install nodelet xml file
add missing build dependency on generated config

This removes a racing condition from the build process.
Merge pull request #25 from v4hn/fix-missing-config-depends

add missing build dependency on generated config