The algorithm for adding parentheses around unary operators was not working properly. It converted a * (-b) * c into a * -b * c, which LSL handles as a * -(b * c).
Fix and add test cases for that. One of the test cases shows an example where the difference matters: 0 * (-1e20) * 1e20 should result in 0.0, but if wrongly parenthesized, it gives NaN, because 1e20*1e20 gives infinity due to float overflow, and minus infinity times 0 is indeterminate.
The addition of parentheses has been improved, but it still does not eliminate every redundant parenthesis.
Also fix the horrendous typo of using "operands" where it should be "operators".
This test suite has been in use for a long time now, in place of the obsolete and unmanageable testparser.py and testfuncs.py. It verifies the complete optimizer output to stdout and stderr, to ensure that the output matches the expectations.
See unit_tests/README.txt for more info.
