More CSV Parsing Improvements

[ylow]

• Allow escape_char to be optional: push a use_escape_char option all the
  way through all code.
• Add csv parsing options true_values and false_values which accept a list of strings to interpret as the numeric value 1, and the numeric value 0 respectively.
• pushed through na_values to the recursive parsers so that missing values inside of dict/lists are handled correctly.
• Filled in the read_json parsing options to correctly map na_values = ["null"], true_values=["true"] and false_values=["false"]
• Better parser diagnostics on parser failure. For instance:

 Unable to interpret ""hello"" as a integer
Parse failed at token ending at:
	2,"hello"^
Successfully parsed 1 tokens:
	0: 2

[ylow]

Do not merge. Fixing a CSV issue in #1263 when there are a lot of CPUs.

[ylow]

ok. ready for review.