feat: Add pause duration parameter

[DenverCoder1]

Summary

Adds a pause parameter to create a delay between lines of text.

By default this is set to 0, you can use it by setting it to a non-negative number of milliseconds to wait between lines:

For a 1-second pause between lines:

...&pause=1000

Try it out on the demo site!

Fixes #118

Type of change

• Bug fix (added a non-breaking change which fixes an issue)
• New feature (added a non-breaking change which adds functionality)
• Updated documentation (updated the readme, templates, or other repo files)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

How Has This Been Tested?

• Ran tests with composer test
• Added or updated test cases to test new features