Optimize sbd_to_rshares to not use an iterative approach

adding weku chain properties

Just a bunch of deleted whitespaces.

We can get rid of the iterative approach by utilizing a few formulars. This makes the function signature smaller as well as improving performance drastically while increasing the precision. 
I also added a few comments to make it more obvious what I'm doing here.

Some more unit tests

beembase/objects: fix serialization of appbase trx

Fix many documentation errors (based on error messages when building)

Refs #72

Added an example to the custom_json section for documentation.

Add get_vote_pct_for_SBD, sbd_to_vote_pct and sbd_to_rshares

This calculates the vote percentage needed for having a given vote value.

Adds the possibility of calculating the needed voting weight for an account with a specified amount of SP/vests

It was slightly unclear that one of the two required auths were needed since both also say optional. Added a note explaining the need for one of the two as well as a block of pseudocode to display the message further.