Pattern namespacing

[morgante]

Right now it's hard to fork/copy patterns from the standard library because you end up with naming collisions between different patterns.

We should relax our requirements here and make module sharing easier.

• Private patterns should only be "visible" inside the same pattern file, and should never collide with names outside the file.
• Other patterns should allow renames in different repos. The name that takes precedence should be the one closest to the target repo. (ie. if I am applying code in repo A but import patterns from repo B any of my named patterns in repo A should override the same names in repo B).