Math data set calculator for:

• mean
• median
• mode
• mid-range
• range
• mean deviation
• standard deviation
• maximum and minimum points
• getting sub-list
• finding values in specified range

Update Log 1:

• Added ability to get a sub set from the entered data set.
  When asked for positions when getting a subset, syntax is (min, max) where min
  is the starting position (starting at 1) and max is the ending position.

Update Log 2:

• Added ability to get a number list made from numbers in a specified range.
  When asked for positions when getting a range, syntax is (min, max) where min
  is the starting position (starting at 1) and max is the ending position.

Update Log 3:

• Added ability to show the help menu by typing 'help' when asked for a data set

Update Log 4:

• Added list value checking for testing if entered list is valid

Please let me know in comments about bugs or things I could do to improve this