Automatic validation of software

Validate software using a test library of functions in a directory.

When developing a software package, it is useful to test changes by periodically running all the functions in a validation library. This function automates the process.

VALIDATE DIRNAME runs each M-file in the directory DIRNAME. Each M-file
should be a function that takes no inputs and returns a logical vector
or scalar. Three outcomes are possible:

'passed' All return values are true.
'failed' Some return value is false.
'crashed' Function threw an error.

A report is generated dynamically in the command window.

VALIDATE by itself tries to find a directory named 'validtests' in the
directory in which validate.m resides.