Apply `ENABLED` / `DISABLED` macros to language-related files.

Edited the European part of 'ISO10646_CN.fon' to match the existing fonts.
Added Chinese font to make_fonts.bat
Created 'dogm_font_data_ISO10646_CN.h'
Added Chinese to 'language.h'
Added 'language_cn.h' with some minor edits.
Added Chinese font in 'language_en.h' to not fall back to European font.
Added cn to 'Configuration.h'
Changed WIDTH to LCD_PIXEL_WIDTH and HEIGHT to LCD_PIXEL_HEIGHT to have more descriptive names.

In 'dogm_lcd_implementation.h'
Added Chinese Font
Made 1 pixel more room for the larger Chinese font on the status line.
Changed geometry of the 'select bar' by one pixel.
Changed the way the position for values and postcars are set.

and add some documentation - how to integrate a new font.

with sources in /fonts