.hgignore
Refactored names to unpopular naming scheme, because (a) bck2brwsr Canvas implementation must be named Canvas due to mapping in bck2brwsr and I don't want interface and impl to have the same name. (b) with the "I" prefix at least it's consistent, even if nobody uses that anymore. (c) names are the same as in HTML5 Canvas Javascript API, so it's more familiar...