Added support for declared signals, and translation of them

[jrbeaumont]

This includes:

• Allows concepts with signals as arguments to be translated
• Allows concepts with signals declared in a data type to be translated
• Keyword for concepts with signals as arguments changed to component to reflect their usage
• Keyword for concepts with declared signals set as system
• Renamed translate/Main.hs to translate/ComponentMain.hs as this is used only to translate component concepts.
• Created translate/SystemMain.hs as this is used only to translate system concepts.
• Added convert function to convert system concepts to a form usable by translation.

[jrbeaumont]

Also note, examples/Celement_with_env_1.hs has been changed to have declared signals for testing purposes.

[snowleopard]

@jrbeaumont Thanks, looks good, just a few comments.

One more suggestion: let's call the files simply translate/Component.hs and translate/System.hs, i.e. without Main. I think it reads better this way.

[jrbeaumont]

@snowleopard: Changes made, if you don't have any further suggestions, let's just check it passes CI before we merge :) Thanks.

[snowleopard]

Thanks! Just one last tweak and I'll merge.

[jrbeaumont]

Done :)

[snowleopard]

@jrbeaumont Merged. Thank you!