Improvements to Java analysis

Changes to existing queries

Query	Expected impact	Change
Equals method does not inspect argument type (`java/unchecked-cast-in-equals`)	Fewer false positive and more true positive results	Precision has been improved by doing a bit of inter-procedural analysis and relying less on ad-hoc method names.
Uncontrolled data in arithmetic expression (`java/uncontrolled-arithmetic`)	Fewer false positive results	Precision has been improved in several ways, in particular, by better detection of guards along the data-flow path.
Uncontrolled data used in path expression (`java/path-injection`)	Fewer false positive results	The query no longer reports results guarded by `!var.contains("..")`.
User-controlled data in arithmetic expression (`java/tainted-arithmetic`)	Fewer false positive results	Precision has been improved in several ways, in particular, by better detection of guards along the data-flow path.

The virtual dispatch library has been updated to give more precise dispatch targets for Object.toString() calls. This affects all security queries and removes false positives that arose from paths through impossible toString() calls.
The library VCS.qll and all queries that imported it have been removed.
The second copy of the interprocedural TaintTracking library has been renamed from TaintTracking::Configuration2 to TaintTracking2::Configuration, and the old name is now deprecated. Import semmle.code.java.dataflow.TaintTracking2 to access the new name.