* Move pkhex.drawing calls out of form constructors
designer doesn't like it; if Main can't be designed then there's some
call that it can't process for whatever reason
* Add netcore3 targeting
Closes#2198 by adding a netcore3 build option
Closes#2391 by retaining designer functionality and net46 builds
Move all sanitization operations from PK* and SAV* to PKX; add general
method for fetching a generation specific string
Changes the Text subform editor to show trash bytes when appropriate.
Special characters to be shown can be easily inserted in the future.
