Create a ${PROJECT_ROOT}/.forge directory rather than ${PROJECT_ROO}/work

[plombardi89]

Many other tools follow the convention of using dot-file directories for storing local project configuration, caches and outputs. Forge should do the same thing. The directory "work" is pretty common and likely to be used already for something by a project.

Other tools:

• git (.git)
• Gradle (.gradle)
• Intellij (.idea)

I can probably think of others, but the convention stands.

[rhs]

This was fixed a while ago.