-normalize `env` and `board` to lowercase naming convention. -make board `name` follow descriptive convention. -implement `-fsingle-precision-constant` compile optimization per https://github.com/MarlinFirmware/Marlin/pull/11178#issuecomment-401673901 -fix typo in 5DPRINT entry.
Co-Authored-By: J.C. Nelson <xc0000005@users.noreply.github.com>
130048 is available on genuine Teensy2.0++ with Paul's "Halfkay" bootloader. Atmel DFU-equiped boards have only 122880 available