v0.3.0

Changes:

• Elf32_Sym and related enums (STB, STT, STV) are moved to elfsect
• Implemented Elf32_Dyn for .dynamic section manipulations
• sections on Elf.sections can now be list of serializable objects (e.g. Elf32_Dyn)

Fixes:

• little-endian ELFs were not read properly
• if sh_type contained unknown value, it was not possible to deserialize object
• sh_type used wrong endianness
• minor fixes