exportMethod:of:on: has of: part omitted
exportClass/Package are now stream writers (have on:)

Less long temporary strings, export should be faster.
exportCategory:on: using composite category object
export package prologue/epilogue has of: part
exportPackage:on: gets a package, not its name
exports' methods have defined structure

all exporting methods have exportStOf: anObject on: aStream,
where anObject is real object (package, class, category, method)

in case of "grouping" methods that just call other methods,
only calling of:on: with same object is allowed, or calling
(self somePartOf: anObject) do: [ :each |
   "same structure, but with each instead of anObject"
].
PluggableExporter, using recipe, exportAll pulled up
*Exporter classes do not inherit from PluggableExporter

They are planned only as sources of recipes
(and repository of worker methods) for PluggableExporter.
Worker methods moved to class-side
recipe moved to class-side
Merge branch 'package-loader-etc' into pluggable-exporters

Conflicts:
js/Importer-Exporter.deploy.js
js/Importer-Exporter.js
st/Importer-Exporter.st
amberc works
Merge branch 'pluggable-exporters' into pluggable-exporters-with-new-loaders
Merge remote-tracking branch 'upstream/master' into pluggable-exporters

Conflicts:
	bin/amberc.js
Merge branch 'package-loader-etc' into pluggable-exporters-with-new-loaders

Conflicts:
	bin/amberc.js
Merge branch 'pluggable-exporters' into pluggable-exporters-with-new-loaders
Merge branch 'master' into pluggable-exporters-with-new-loaders
Merge branch 'master' into pluggable-exporters-with-new-loaders
Merge pull request #576 from herby/pluggable-exporters-with-new-loaders

Pluggable exporters