sigfigstr - printing with the appropriate number of sigfigs

This function is aimed at creating formatted strings of numbers with the appropriate number of significant figures, whether large or small.

This function formats strings based on the desired number of significant figures rather than the number of decimal places. It is inspired by work on stack overflow (https://stackoverflow.com/questions/21354701/matlab-fprintf-to-keep-significant-figures-and-rightmost-zeroes).

Here is an example of it in action
>> sigfigstr(.000012431634,3)
ans = '0.0000124'
>> sigfigstr(26666,3)
ans = '26700'

I welcome any feedback or notes of when it doesn't work.