Add config extends and entry point exclusion

Profiles may inherit from another config file (extends: <path>): the
first profile of the referenced file is merged underneath (scalars from
the overlay win, slices concatenate base-first and de-duplicate, chains
resolve recursively, cycles are detected).

esbuild.excludeEntryPoints removes merged entry points by glob (** spans
path separators, * stays within a segment), applied after path
resolution so patterns and entries match in the same shape.

Lets product editions/flavors (e.g. the wmd4x Range Trader Pro edition)
build only their own entry set on top of a shared, merge-clean base
config. Includes unit tests and template docs.

main.go

@@ -26,7 +26,7 @@ func main() {
 	app := &cli.App{
 		Name:    "gowebbuild",
 		Usage:   "All in one tool to build web frontend projects.",
-		Version: "7.5.0",
+		Version: "7.7.0",
 		Authors: []*cli.Author{{
 			Name: "trading-peter (https://github.com/trading-peter)",
 		}},