feature: single line progress reporter

Invoked by passing "--reporter=singleline" to bandit on command line.
Copied from dots_reporter. A lot of duplication.

Possible to select reporter with "--reporter" argument

Building out-of-source builds with vim

Fixed intentionally failing test that got committed by mistake.

vimrc: Current directory is restored after build.

feature: Single line progress reporter

This progress reporter uses a single line that gets updated
with the number of tests executed and how many have failed.

Used by invoking bandit with "--reporter=singleline"
build: making it easier to use out of source builds.