Add dash support

[robzr]

• Rewrote functions that depended on Bash specific features where easily done; and tested as a function library with Dash/Busybox. New syntax had the side effect of a massively faster sort routine; then changed the Bubble sort to an Insertion sort for another bump in speed.
• Added min/max functions
• Added sub version filters that can be used with stdin commands (filter, min, max, sort), also works with equals, constraints
• various work on constraints
• added tests for new functionality