Fix whitespace and blank lines in trimstr and read_all_lines.

[nishihatapalmer]

• trim_str had a bug - if string was empty would dereference line[-1]
• also ignore space and tab characters to trim those from the end.
• read_all_lines should only copy in the algo if the string isn't empty.

This makes processing the selected_algos more resilient - spaces and blank lines are ignored. Fixes issue #4