Added test for case 0,1,0,0 -> 1,0,0,0, renamed existing middle test
Added code to tilt.c to pass following tests:
Value on right shifts to left edge after shift - PASSED.
Value in (right) middle shifts to left edge after shift - PASSED.
Value in (left) middle shifts to left edge after shift - PASSED.
Distinct values don't combine - PASSED.
Refactored move to left operation to own method tiile_line_left
Added tests for slide_to_left function
disabled all higher level tests
implemented test case for two individual elements
enabled test case for two individual elements
added test case 1,0->1,0 ie value on left stays on left