fixed some whitespace handling

I added some code to robustly handle obj files with extra spaces. The code in the repository is not able to parse the following:

* lines with leading spaces (e.g. in the inline obj example from README)
* lines with multiple delimiting spaces (e.g. ```v 1 0 <multiple spaces> 1```)

This commit fixes the above problems. Javascript split() function is hard to customize, so this required some extra code.