Replacing Operations in SFG

Description of issue:

Given a valid SFG, the user should be able to replace any operation with another operation(s) with the same amount of in/output ports.

Linked Requirements:

( 23 )

Potential Issues:

None

Blockers:

( #8 (closed), #12 (closed), #13 (closed) )

Issue Requirements:

1. Any operation in a SFG should be able to be replaced with another operation with the same amount of in/output ports. The resulting SFG should be valid.
2. Any operation in a SFG should be able to be replaced with another set of operations with the same amount of in/output ports. The resulting SFG should be valid.

Comment:

The resulting SFG should be valid according to #12 (closed).