SI-4829 The :load command now fais if the command ends with a space

Modified the load command to accept a variable amount of filenames and to ignore whitespace at the end of the command.

I am aware that this pull request cannot be accepted in  it's current form. I am looking to gather feedback on what I have done up until now, as not to waste too much time going down the wrong path (i.e. writing documentation for the methods I added). I am also aware that this would need to be rebased against master if I were to actually add these methods.

Review by @paulp, @phaller, @axel22