Fixes #2085 path equality overrides

[Dunbaratu]

Fixes #2085

There were a couple of things causing this:

1 - While GlobalPath.Equals() has the right logic in it to test equality, PathValue.Equals(), in the PathValue class which is a wrapper around GlobalPath, wasn't using it.

2 - Even with Equals() properly defined, it still wasn't getting invoked because kOS only uses the == operator for equality. (i.e. the kerboscript definition of == for comparing two Structures always has to match the C# definition under the hood for it.) This is because of how CalculatorStructure.Equal() invokes the method op_Equality (via reflection) to do the test.

The code changes here implement those operators for Path.

Here is a more complete version of the tests mentioned in the orginal issue #2085 . When running it, just check to make sure the expected value printed matches the actual result after the colon:

// In order for consructor PATH("somestring") not to crash the script,
// I have to ensure that somestring is a valid path on the volume:
if not exists("1:/file1")
  log "test file 1" to "1:/file1".
if not exists("1:/file2")
  log "test file 2" to "1:/file2".
if not exists("1:/file3")
  log "test file 3" to "1:/file3".

LOCAL pathA IS PATH("1:/file1").
LOCAL pathB IS PATH("1:/file1").
LOCAL pathC IS pathA.
LOCAL pathD IS PATH("1:/file2"). // path which should differ from the rest.

// Tests which should all be TRUE:
PRINT "T1. Expect True: " + (pathA = pathA).
PRINT "T2. Expect True: " + (pathB = pathB).
PRINT "T3. Expect True: " + (pathA = pathC).
PRINT "T4. Expect True: " + (pathA = pathB).
PRINT "T5. Expect True: " + (pathB = pathC).
PRINT "T6. Expect True: " + (pathA <> pathD).
PRINT "T7. Expect True: " + (pathB <> pathD).
PRINT "T8. Expect True: " + (pathC <> pathD).
PRINT "T9. Expect True: " + (pathA:TOSTRING = pathB:TOSTRING).

// Same, but reversed left/right operands:
PRINT "TR1. Expect True: " + (pathB = pathA).
PRINT "TR2. Expect True: " + (pathB = pathB).
PRINT "TR3. Expect True: " + (pathC = pathA).
PRINT "TR4. Expect True: " + (pathB = pathA).
PRINT "TR5. Expect True: " + (pathC = pathB).
PRINT "TR6. Expect True: " + (pathD <> pathA).
PRINT "TR7. Expect True: " + (pathD <> pathB).
PRINT "TR8. Expect True: " + (pathD <> pathC).
PRINT "TR9. Expect True: " + (pathB:TOSTRING = pathA:TOSTRING).

// Tests which should all be false:
PRINT "F1. Expect False: " + (pathA <> pathB).
PRINT "F2. Expect False: " + (pathA <> pathC).
PRINT "F3. Expect False: " + (pathA <> pathA).
PRINT "F4. Expect False: " + (pathB <> pathB).
PRINT "F5. Expect False: " + (pathC <> pathC).
PRINT "F6. Expect False: " + (pathD <> pathD).
PRINT "F7. Expect False: " + (pathA = pathD).
PRINT "F8. Expect False: " + (pathB = pathD).
PRINT "F9. Expect False: " + (pathC = pathD).

// Lexicon example setup:
LOCAL pathLex IS LEX(
    pathA, "file1",
    pathD, "file2"
    // file3 is not present on purpose so we can test missing key cases
    ).

// Note that AFTER setting up the Lexicon, we'll change
// the value of pathA to match what pathD had been.
set pathA to PATH("1:/file2").
// Expected result: Now we should have:
//  pathA = 1:/file2
//  pathB = 1:/file1
//  pathC = 1:/file1
//  pathD = 1:/file2

PRINT " L1. Expect Value file1: " + lexValAt(pathLex,PATH("1:/file1")).
PRINT " L2. Expect Value file2: " + lexValAt(pathLex,PATH("1:/file2")).
PRINT " L3. Expect failure:     " + lexValAt(pathLex,PATH("1:/file3")).
PRINT " L4. Expect Value file2: " + lexValAt(pathLex,pathA).
PRINT " L5. Expect Value file1: " + lexValAt(pathLex,pathB).
PRINT " L6. Expect Value file1: " + lexValAt(pathLex,pathC).
PRINT " L7. Expect Value file2: " + lexValAt(pathLex,pathD).
SET pathD to PATH("1:/file3"). // Note, construct new value for testing:
PRINT " L8. Expect Value file2: " + lexValAt(pathLex,pathA).
PRINT " L9. Expect Value file1: " + lexValAt(pathLex,pathB).
PRINT "L10. Expect Value file1: " + lexValAt(pathLex,pathC).
PRINT "L11. Expect failure:     " + lexValAt(pathLex,pathD).

PRINT "--Done--".

// A way to print a lex key without breaking execution if not found:
function lexValAt {
  parameter lexStruct, lexKey.
  if lexStruct:haskey(lexKey)
    return lexStruct[lexKey].
  else
    return "((key not found))".
}