Breaking change to utils.strlen in 0.3.7

[adrianosmond]

Previous to 0.3.7 utils.strlen converted anything passed into it into a string while stripping it via
var stripped = ("" + str).replace(code,'');

As of 0.3.7, str is passed directly to stripAnsi:
var stripped = stripAnsi(str);

This means that anything that isn't a string is being passed into it it now breaks in a way that it didn't in 0.3.6. I came across this because @lingui/cli is passing numbers into a table

[adrianosmond]

Apologies. This is a duplicate of #152. I'm closing it.