[Feature] Added concurrent info for single progress bars

[gregormaclaine]

This feature adds new methods to the SingleBar where the user can show additional information about the process on the single line immediately below the progress bar.

Reasoning

I wanted this feature in my own project, because I had a process that went through multiple files and ran a long process and I wanted to see exactly which file was currently being processed. This allows that by giving that information below.

Example

Note: This is the output from the new example file

Note on use in Multibars

As this feature adds text immediately below the progress bar, it does not really fit with the functionality Multibar, as by definition it is doing multiple different processes at the same time. Therefore I updated the options such that this concurrent info feature cannot be used in a Multibar i.e. the functions will do nothing.

Change Log

• Added base concurrent info feature
  • Additional modifications to account for clearOnComplete option
• Added example-concurrent-info.js example file
• Added restrictions to prevent this feature being used in a Multibar
• Updated README doc with information about how to use the new feature