runCommand should take an array of strings instead of a string

[CyberShadow]

Hello and thank you for creating this invaluable project.

I think it would be better if the runCommand method accepted an array of parameters, instead of a parameter string.

• Currently, it is not possible to pass arguments to OpenSSL containing spaces, or empty arguments. The minimalistic splitting code used by openssl.js splits only by continuous runs of whitespace.

• Careless users of openssl.js may not sanitize input, thus allowing injection of arbitrary OpenSSL arguments. This might lead to security problems.

The parameter I encountered this with was the -challenge option for openssl spkac, when implementing a polyfill for the deprecated <keygen> tag. <keygen> has a challenge attribute which should be passed to this option, so the library should be able to pass any string that can occur in a DOM attribute node.