Fix tdv2100 display edge-cases

[Frodevan]

I had a closer look at the schematics and a few of the jumper-settings in the manual, and realized a few things:

1. A handful of jumpers had their polarity wrong, leading to wrong default settings
2. The latching of the attribute happens on the rising edge of the character-clock, i.e. active with the character immediately following the change

In particular nr.2 does make a difference, since attribute-effects are not blanked even when the attribute-change character itself is blanked. This difference can be seen when changing away from an underline or inverse attribute (also when changing away from low-intensity if global inverse-video is on).

Marking as draft for the time being, until I get the time to verify the attribute-change behavior on real hardware.