Add Ecore generator

[Matthias Schoettle]

Add a generator which creates an Ecore model for the structural view of an aspect.

[Matthias Schoettle]

Merged in EcoreGenerator (pull request #88)

Resolves #461: Add Ecore Generator.

→ <<cset 27411ca2ade4>>

[Matthias Schoettle]

References #461: Fixes an issue when the aspect is not saved.

Uses the last known generator folder if the aspect was not saved, otherwise the aspect's parent folder is used for the suggest absolute file name.

→ <<cset 1e90236937ed>>

[Matthias Schoettle]

References #461: Fixes an issue where a permission denied exception is thrown for file names.

File.canWrite returns false if the file doesn't exist yet. Since exceptions from the EcoreGenerator can be caught directly, it is only necessary to check prior to calling the Acceleo generators since exceptions cannot be caught during their generation.

→ <<cset 897fefe92c25>>

[Matthias Schoettle]

References #461: Adds Checkstyle properties.

→ <<cset fa498b0c35eb>>

[Matthias Schoettle]

References #461: Adds file extension to suggested file name.

Otherwise, in case a directory with the same name exists, the directory is selected.

→ <<cset 3e18b7c80d41>>