Closes#3177
Format sizes are now accurate to game structure sizes. Added a few more editable fields, rid of label/textbox/etc for general base editing -- use a PropertyGrid instead.
Feels nice having a bank of saves to reference + idb to discover the struct layout.
* 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