Implemented reading calibration file
 - read "calibrated.xml" for camera matrix and distortion coefficients from successful camera calibration
 - display undistorted output
 - TODO: specify calibrated xml filename in default.cfg config file
Load claibrated xml from default config xml
Undistortion on GPU
 - undistortion uses combination of initUndistortRectifyMap() (CPU-bound) and ocl::remap() (GPU-bound) functions to replace the CPU-bound undistort() function
   - undistort() = initUndistortRectifyMap() + ocl::remap
 - test results on AMD Radeon R9 290 + Intel i5 4670K: