Removed some dangling notes

Schematics refactoring: - New sheet reserved to video memory. - Removed video memory parts inside video_generation. - Removed video memory parts inside GPIO. - Generic cleanup to keep all circuits inside each sheet.

Discovered WE and OE signals for video memories, plus others

Something else in video generation sheet

Found vsync frame signal for z80 + minors

Added some missing labels and references

Video memory concurrency - bank7 selector to address video or attribute RAM - found read and write data paths leading to video RAMs (F11, F12). - video RAMs CS generation.

Other steps in video generation - Some notes regarding video attributes. - Found some stuck-at inputs.

A long job in analog video output ! Read comments inside video_memory_management sheet for more informations. - Completed path between dot pattern output of character shift register and beam output transistor. - Found behavior of video attribute signals: blink, underline, stretch, hide. - Completed wiring of 28L22 ROM, which is involved in video attributes. - TODO: video_memory_management must be cleaned up, since schematics has grown outside sheet.

Discovered bank 0 + fixed wrong signals in video gen