Started merging 2.x branches tasks,emul,crawl:
* add skeleton of emulator module (emul class)
* reorganize system modules into subpackages
* add System, OS, Task and DefineStub classes
* add AVR architecture
* modified block class => map attribute moved to cfg.node class
* moved memory classes in system.memory module
* moved cfg analysis classes in 'sa' subpackage
* improve debug logs
* improve PE/ELF parsers with amoco.structs module
* add checksec method in Elf class
* HUGE fix of armv7 semantics and formats