path planning mathod based on cubic spline

• This project gives an example, which can be modified by users.
• Every block during option start and option end should be modified by users according to the actual situation, where contains printing options.
• Need to pre install dependency Eigen:
  sudo apt-get install libeigen3-dev
sudo ln -s /usr/include/eigen3/Eigen /usr/include/Eigen
• Provide simple parameter type checking function.
• Control points should be expressed in a matrix P_, each column of this matrix represents a control point given by the users and this matrix should contains the start point at the first column and the end point at the last column.
• The coefficients of each segment of the whole path are loaded in CS->a, CS->b, CS->c and CS->d after run the function CS->CubicSplineRun, if you want to know the specific form of the equation corresponding to each paragraph, please do not commented macro definition CUBICSPLINE_TEST_PRINT_EQUATION.
• Parameters NATURAL, CLAMPED and NOT_A_KNOT means different end condition, could be use as CS->CubicSplineRun(control_pt, NATURAL) or CS->CubicSplineRun(control_pt, CLAMPED) or CS->CubicSplineRun(control_pt, NOT_A_KNOT) in the example in main.cpp.
• The test result is as the follow figures, the red line corresponds to NATURAL， the blue line corresponds to CLAMPED and the green line corresponds to NOT_A_KNOT. Control points are set as (0, 0) & (2, 6) & (3, -1) & (7, 0), all of them are plot as the black dot in the figure.

• Reference:
  三次样条插值(Cubic Spline Interpolation)及代码实现(C语言)