2.3.2 Improved usage, ETC estimation, restored slow receive warning msg

• #29 Custom Variables From Selector Not Being Passed - Adjusted the regex pattern to include "-" and "_" in property names.
• #30 Estimate time providing unrealistic estimates - Updated ETC logic to take last 10 (configurable through NUM-TPS-FOR-ETC option) tps estimates taken at 30sec intervals instead of total average tps from the start. The ETC will print "0:00-1 (paused)" if the job is paused and use the new tps values after the job is resumed.
• #31 Add printing of (better) help/usage to console - Provide more expansive usage statements listing the available CoRB2 options.
• #32 Provide an easier way to extend ModuleExecutor and customize handling of ResultSequence - Change visibility of processResult() and writeToFile() methods to protected, in order to facilitate extensions and method overrides.
• #33 The latest corb removed WARNING: Slow receive! Consider increasing max heap.. - restored the warning messages that had been dropped in v3.2.1. Added logic to change INFO statements to WARNING if available memory is less than 20% of total RAM.