Exception handler detection that is independent of address ranges

[Washi1337]

Summary:
Currently, Echo can only automatically detect and subdivide a control flow graph into exception handler regions if it is provided a collection of address ranges. This makes the assumption that nodes within a single exception handler region are close together in memory. That is, every node within a protected region is within a certain starting and ending address. This is true for platforms such as CIL and the JVM, but this might not be true for others, like x86 or custom virtual machines. The suggestion is to add support for automatic subdivision of a control flow graph through other means, such as a collection of nodes instead.

Suggestions:

• Add an overload to DetectExceptionHandlerRegions, taking a collection of exception handler info objects, where each info object consists of the set of protected nodes, as well as the set of nodes making up the handler region.

  In the case that sets overlap, Echo is then expected to nest EHs based on which sets of nodes are fully enclosing other sets of nodes.

• An even more advanced version of DetectExceptionHandlerRegions could just accept a collection of exception handler info objects, where each object only contains the starting node of the protected region, as well as the start of the handler node. Echo is then expected to automatically infer the full range of nodes that are included in the regions automatically (e.g. by dominator analysis).