Typo in comment.
Wrote test cases for equality, and fixed equality in RegexCond

Wrote test cases to ensure consistency between hashCode, toString, 
and equals. Had to fix RegexCond accordingly.

Removed the super.equals, super.hashcode, and super.toString calls,
since these revert back to Object, which in turn gives pointer
equivalence. (Such super calls are only useful if the superclass 
defines structurally equivalence as well).

Since the Pattern class has no structural equivalence, I replaced
the Pattern equality check used in equals by an equality check on
the String representation.

Todo: 

* fix other condition Condition classes having same problem;
* turn test cases into parameterized test covering all Conditions.
Turned ConditionTest into parameterized test.
Added test case for NotRegexCond, and fixed its hashcode/equals impl.
Test case for UrlCondition, and fixed its hashcode/equals method
Test case for NotUrlCondition, and fix for its equality/hashcode.
Testcase for (Not)XPathCondition + fix of equals/hashcode.

Also added explanatory string in Parameterized test case.
Working on #241
Working on #241. Problem of the positioning seems to be that Position.getY() returns a weird value.

- Also fixed big error prints when the crawler leaves the domain.
- The faulty `getY()` stuff is now printed too.
Test cases for VisibleCondition + fix for equality/hashcode
Tests for NotVisibleCondition + fix for equals/hashcode.
Test for JavaScriptCondition + fix for equality / hashcode.
Improved comment.
Equals/hashcode/toString and tests for Logic.not
Equal/hashcode/toString and tests for Logic.and
Merge pull request #271 from daisy1754/master

refactoring: fix spell 'Invriant' -> Invariant
Hashcode and equals in Eventable now also take source and target into account.

Fixes #155
Merge branch 'fixes/155-fix-elements-without-interactions' into fixes/241-candidate-position-out-of-place
Deleted temporary test
Removed more debug stuff