faster GLCD (ST7920 SW-SPI) implementation / fixes

- fixed long menu entries (>14 or >18 chars) caused overrun in dogm lcd
implementation
- fixed pin set problem when in interrupt
- much faster ST7920 SW-SPI implementation
- increased ST7920 framebuffer size for more speed
Merge pull request #505 from MStohn/much-faster-glcd-st7920

faster GLCD (ST7920 SW-SPI) implementation / fixes