Generate lensish API

[cblp]

-- now
note_status_assignIfDiffer newStatus = do
    curStatus <- note_status_read
    when (curStatus /= newStatus) $
        note_status_assign newStatus

-- should be
assignIfDiffer new = do
    cur <- read
    when (cur /= new) $
        assign new

- note_status_assignIfDiffer
+ note_status &~ assignIfDiffer

[dpwiz]

Maybe make a ron-lens package with all the fancy stuff for those who like such things?

[cblp]

The problem is that lenses must be generated from the schema, so they go to ron-schema-gen or something like that.