Allow PowerJS to start when PowerShell profiles take a long time to load

As described in #12, PowerShell will write a message to `stderr` if loading the PowerShell profiles takes longer than 500 ms, causing an error to be thrown when `PowerJS` is instantiated. This pull request allows the instantiation of `PowerJS` even when the profiles take more than 500 ms to load by altering the statement checking `#readerr` to instead check a copy of `#readerr` that has had all matches to the RegEx `/Loading personal and system profiles took \d+ms\./g` replaced with the empty string and extraneous whitespace trimmed away. Closes #12.