init
made test more resonable
parameter for printing only every n'th coordinate index
comments
added TODO file
calculation of dynamic printlength of index values

used to shift and resize the whole matrix if indexes are too long
added 2 test functions
updated TODO accordingly
Fixed a bug with the printing of the X-Axis

because the x-axis partial-string was printed "number_of_y_values" many times it could be too short or too long
now it is printed "number_of_x_values_per_row" many times
cleanup
matrix handling (subs and tests)
finished generating a matrix from a list of values, plus fixes for bugs which occurred along the way
TODO update
support for large x- and y-ranges

additionally, a step length can be set for both axis individually to correctly compute the index values
y-lo in plot_matrix is now also obsolete, due to the steplen approach
plot_matrix: accounting for negative index ranges

if the x- or y-indexes can become negative in sub plot_matrix, we now increase the corresponding offset value
to keep a neat printing layout
TODOs, cleanup and one important index check
added TODO item
added option parsing and tried to print a matrix, introduced a bug earlier, matrix is printed as all undef
fixed condition in index checks in matrix_set_value
fixed matrix printing with actual values
all starting options and a usage function