split: Split trajectories in several parts

If SPLIT_FUTURE is 1, each data file is split after each line where
the last column is 0.  If SPLIT_FUTURE is 0, each file is split into
two parts.  If not set, SPLIT_FUTURE defaults to IF_FUTURE or to one.
split: Split pca data in main directory
downsampling: Basic structure
downsampling: Down sampling for all starting points

Split data is written to splitdata/ in main directory,
or, for the standalone version, in current directory.
If data shall not be split, SPLIT_FUTURE is set to 2.
downsampling: Compatibility with SPLIT_DROPSUFFIX
downsampling: Target and links for use in main dir
fileinfo: Basic structure
fileinfo: Get number of data columns in files

The number of columns minus IF_FUTURE is determined once
and then saved to variables NCOLS_file to be used again.
fileinfo: File lists with -V01 or -V01-V02 suffix

Single or double indices run up to the minimum of file
specific NCOLS_file and global name_LAST_COL variables.
The second macro argument is an additional suffix.
fileinfo: File lists with enumerated plot suffixes

The index runs up to the minimum integer such that name_PLOT_NCOLS
columns are considered per file with a total number of name_LAST_COL
or NCOLS_file columns. The second and third argument of the add_01
macro allow to specify additional suffix parts around the number.
fileinfo: Performance increased by using variables