usage: [-n new_location] [-r newName] <source srt> <shift by>
<source srt>: the source srt
<shift by s seconds>: shift by s seconds, can be a floating point value and/or a negative value
-n: create new srt file in a new location, option arg = new location, if this option is not given, the srt is saved in the same directory as the old srt file. Furthermore, if the following -r argument isn't given, then the initial srt file is truncated instead
-r: rename to be created srt file, option arg = new name, if this option is not given, the name of source srt is used