Refactor SplitR folder tree existance/creation
Revise comments
Return path of SplitR folder twice in the script

Previously, this information was only collected in
the conditional branch where creation of SplitR
folders was performed. The SplitR path string will
be needed later even if those folders existed.
Remove statement that sets a new working directory
Revise comments
Create the help file for the ‘project.define’ function
Create function stub for ‘trajectory.plot'
Edit the text and add examples to help file