SC: change default contract type

[bchamagne]

Description

Change default contract type from transfer to contract. We can now have contracts that don't necessarily have transfers. Plus added data & contract types as valid argument to the set_type action.

Fixes #844

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

Tested this scenario via the transaction builder:

condition inherit: [
	content: true
]

condition transaction: [
	uco_transfers: size() > 0
]

actions triggered_by: transaction do
	set_content "hello"
end

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules