Steps should have Evidence sub-objects

[LeeBergstrand]

Problem Description

Currently steps can have multiple pieces of evidence supporting them. These are marked by separate EV and TG tags.

For example:

--
SN  5
ID  N-(5'phosphoribosyl)anthranilate isomerase
DN  N-(5'phosphoribosyl)anthranilate isomerase (EC 5.3.1.24)
RQ  1
EV  IPR001240; PF00697; sufficient;
TG  GO:0000162;
EV  IPR010188; TIGR01919; sufficient;
TG  GO:0000162;

In the current system we do a preprocessing pass that collapses the EV and TG tags to a single tag per step.

EV  C1
TG  C2  ==== Goes To ====>> EV C1; C3;
EV  C3                                           TG C2; C4;
EV  C4

Problem Solution:

Each set of EV and TG should be pulled out into their own EVIDENCE object. Note: The sufficient key word means that that piece of evidence alone proofs that the that step exists (Ref: ebi-pf-team/genome-properties#30).

[LeeBergstrand]

The plan is to wait for genome properties to solidify their flat file format with respect to steps before pursuing this change.

See ebi-pf-team/genome-properties#29 and ebi-pf-team/genome-properties#31

[LeeBergstrand]

Done. Via #9