Detect variable type per code-block using 'instanceof'

[addiks]

Currently every variable has one hard type per executed routine. This type is determined by the first type-declaration of this variable. Often this is not enough as a variable that was declared as a general type will be tested as a specific type (using "instanceof") and if true will be treated as this specific type. This plugin cannot yet reflect this "type-specialisation".

In the future the plugin should first try to detect the type of a variable at the place where the type was asked. For example it should look for occurrences of "instanceof" in or on the execution-branch that the place to analyze is in.