Add utility method `MCRepository >> storePackage:`

Make all repository types to store info change record ...not only `TonelRepository`. Not that other repository types are used anymore, but won't hurt.

Oops, add missing `MCStXPackageInfo >> projectDefinition`

Fix load ordering w.r.t pool dictionaries In Smalltalk/X, pool dictionaries should be present before classes using then are defined.

Use custom Smalltalk/X package loader(s) This commit add a custom `MCStXPackageLoader` which reads a project definition (or package manifest in Pharo parlance) first and consult it for dependencies and/or pre-load action. This unifies loading native Smalltalk/X packages and (main) Pharo tonel packages and allow for automatic dependency resolution.

Always include `PackageManifest`s even if not including St/X extras This done to improve interoperability with (Pharo) packages.

Fix writing packages consisting of extension methods only

Do not cache `MCVersion`s in cache repository

Filter out synthetic methods when creating snapshots

Remove trailing new line in methods source This commit introduces a terrible hack. In Squeak / Pharo world, the method source does not (shall not?) contain trailing new lines. St/X browser, OTOH, puts a trailing new line in methods' source. So, when code is loaded into St/X and modified then saved back, it adds an spurious extra trailing line. This creates a noise, especially when using Tonel. It gets worse. I (JV) did not pay attention to this problem before and start hacking, already adding a spurious new lines to considerable codebase - too bad. To fix while avoiding noise in diffs, we remove trailing newlines for modified methods. However, we have to save back source without trailing new lines to the method itself so that when the package is saved again from the same image, it won't add the new line (because second time the method is no longer 'modified'). Complicated, isn't it? Stupid, isn't it?