{Issue #47} Synchronous spinner

[foster999]

Description of new feature, or changes

Added the ability to manually render single spinner steps, via:

• 'manual_step' argument when creating Halo class instance
  • '.step()' method to trigger single frame to render
  • 'test_manual_step' test

Usage

with Halo(spinner='dots', manual_step=True) as spinner:
    for text in ["foo","bar"]*5:
        spinner.text = 'Loading {}'.format(text)
        spinner.step()
        do_something(text)

or

spinner = Halo(spinner="dots", manual_step=True)
spinner.start()
for text in ["foo", "bar"]*5:
    spinner.text=text
    spinner.step()
    do_something(text)
spinner.stop()

Checklist

• [x] Your branch is up-to-date with the base branch
• [x] You've included at least one test if this is a new feature
• [x] All tests are passing

Related Issues and Discussions

Fixes #47 (new feature)

People to notify

@steelman

[coveralls]

Pull Request Test Coverage Report for Build 420

• 19 of 19 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-1.01%) to 90.008%

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Totals
Change from base Build 409:	-1.01%
Covered Lines:	949
Relevant Lines:	1035

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💛 - Coveralls