Ethereum address checksum encoding

[RebeccaSelvaggini]

No description provided.

[jaromil]

Well done!!! Can you also clearly state in the documentation that for checking the validity of an imported ethereum address one needs to read it also as string?

Given I have a 'string' named 'ethereum address' 
When I verify the ethereum address 'ethereum address' is valid

This is perhaps a good start for an example (taken from the test unit). The documentation should show a real-case scenario in which an address is imported, checked and then used to create a transaction. Reading the code now I'm not sure if its the case that the address needs to be imported twice, as schema and as string...

[jaromil]

last force push is just the conflict resolution for minor conflicts caused by recent changes merged in master.

By doing so I have broken something in the export, sorry! can you find out a fix? after this last test is fixed this can be merged, the documentation task is addressed in #664 and can be developed in a different PR

[jaromil]

well done!!!