USAGE
fig_print(fig,figname)
fig_print(fig,figname,dim)
fig_print(fig,figname,dim,crop)
fig_print(fig,figname,dim,crop,magn_factor, bg_color)

INPUT
- FIG: figure handle
- FIGNAME: file name, including extension (BMP, JPG, PNG or TIF)
- DIM: 1x2 numeric array with the image dimensions. If DIM=[], the current figure size times MAGN_FACTOR will be used.
- CROP: 1 (crop image) or 0 (do not crop [default]). Remove homogeneous edges
- MAGN_FACTOR: magnification factor (any positive number). Only effective when DIM=[]. Default: 1
- BG_COLOR : If specified, the figure window background color will be changed. You can specify a color using a three-element vector of RGB values or one of the MATLAB predefined names (short name: 'y', 'm', 'c', 'r', 'g', 'b', 'w', 'k')

OUTPUT
- FIGNAME in the current folder or in the folder specified by its path. The file format depends on the given extension.