* accounts/abi: implement new fackball functions
In Solidity v0.6.0, the original fallback is separated
into two different sub types: fallback and receive.
This PR addes the support for parsing new format abi
and the relevant abigen functionalities.
* accounts/abi: fix unit tests
* accounts/abi: minor fixes
* accounts/abi, mobile: support jave binding
* accounts/abi: address marius's comment
* accounts/abi: Work around the uin64 conversion issue
Co-authored-by: Guillaume Ballet <gballet@gmail.com>