legacy plugin: better compatibility with old brd files (current track width and current vias size, stored in SETUP section, were not read from file and incorrectly set)
- re-worked PNS_LINE_PLACER and PNS_ROUTER classes a bit, removing duplicate class members
- cleaned up Andrew's blind/buried via fixes
- fixed 'custom via width' dialog bug updating the width even when closed/cancelled
- fixed incorrect radius of drawn microvias