Support for RRA modification command line syntax
allow to remove RRAs entirely
factor out rrd file writing in rrd_modify_r
Make it possible to add / remove a given number of rows for existing RRAs
Allow RRA resize to absolutely specified row_count
Factor out RRA definition parsing so it may be reused for rrdtool modify.
make parseRRA and handle_dependent_rras globally available
factor out init_cdp and make it globally available
Fix CDP init problems introduced with original add DS code
Allow to add new RRAs
add support for explicit DELRRA