Add binary tree test function
Create test subdirectory

Set up the autotools configuration for a separate test subdirectory,
with just a simple binary tree test for now. The idea is that
interactive programs go in src, and test programs go in test.
Move non-interactive factorial program to test
Remove all tests from src directory
Remove unneeded include
Whitespace
Move sort testing code to separate header file
Simplify sort program and add title output
Add sort test program
Whitespace
Remove hardcoded count
Move stack_with_min program to test directory
Move linked list assertions to test program
Merge branch 'test_subdir'
Add clarifying comments and output to shuffle program