Support for obtaining the minimum and maximum of a distribution

[haykam821]

For example:

> d2
  1: 50.00%  ##############################
  2: 50.00%  ##############################

> min d2
1

> max d2
2

Some things to consider:

• Would there be conflicts between min and the minutes unit?
• Would it make sense to support multiple arguments, such as min (1, 2, d8 + 5) returning 1?
• If so, would multiple units be supported (with incompatible units being an error)?