#4 Make kicad5 and each stable release hereafter an official tool to work with files

### Issues solved: * contributors needing to downgrade and find old versions. * contributors being unable to contribute to layout with official tool because it is in kicad5 since metacollin. * tons of issues and general sluggishness and poor ergonomics of using kicad4 * being unable to use some general kicad features and autochecks because of the requirement of keeping layout and sch in separate versions. *Which abscence of possible sync actually makes both pcb and sch more error-prone. I shoveled metric tons of kicad-unrelated sch and pcb errors after metacollin, most of which would never happen if kicad files were in sync. In fact I detected them by trying to make sync and seeking for a root cause of incompat.* ### Issues created: * kicad5-specific issues... *which I haven't really encountered much of... even working with it for several months already. even using countless unfinished git versions. (the only time i updated a git version and sth went wrong is Edit shortcut E not always working) even with my custom-compiled mesa drivers which is sort of an indicator.* * eeshow needing an upgrade to devour new format. (even if wpwrak won't do it, I will do it myself)