#94 Fixed issue where parsing font values with trailing commas causes…

[SebBrookfield]

… an IndexOutOfRangeException.

When dealing with a property value with a trailing comma, the code would try to start from that comma, and increase the start index by one. This would cause the start index to go out of bounds since it was the last character in the string.

Also removed the check for start being greater than -1 since the start index is never decremented. This fixes #94.