Big files and Progress

[christopher-mangion]

• Added a simple parquet converter to convert parquet files to csv with the same name in the same directory
• Updated ProgressBars to now have normal, updatable, and steppable versions
• Updated BigFileWriter populateFromFolder to now default to it's defined subfile directory
• Updated subfileExists to getSubfileNames as the former was inefficient for repeated calls
• Updated BigFileWriter to now use a progress bar for displaying oneFile combine progress
• Fixed a bug with BigFileWriter where not all columns were being added to the header in specific situations