Add metamodel import & merge capabiility

[tomasz-zajac-volantis]

Context

In the current solution, the metamodel is embedded in the project. There is no option to extend or change the current metamodel.

Solution

Add capabilities:

• Import the metamodel
• Merge external metamodel with the project embedded
• Metamodel can be loaded from a local file or remote/web source (i.e. Radical Tools Metamodel Store)
• Metamodel can be exported from project