MEGA65: full colour MCM #419

The VIC-II legacy "MCM" mode (4 colours given by 2 bits / pixel) uses
data read from colour RAM for bit combination "11". In MCM char mode
the low 3 bits of that data can be used as colour index, as bit 4 tells
if the character is MCM at all. In bitmap mode, the full 4 bit can be
used. However on MEGA65 we have 8 bit wide colour RAM, which can then
use all the 8 bits. $D063.6 controls this feature.

This is currently experimental, there can be problems!

The issue has been reported by @TheChief

Introduced in branch next.

Author: lgblgblgb

targets/mega65/vic4.c

@@ -1519,7 +1519,7 @@ static XEMU_INLINE void vic4_render_char_raster ( void )
 					SXA_HORIZONTAL_FLIP(color_data),	// hflip?
 					palette_now
 				);
-			} else if ((REG_MCM && (color_data & 8)) || (REG_MCM && REG_BMM)) {	// Multicolor character
+			} else if ((REG_MCM && ((color_data & 8) || (vic_registers[0x63] & 0x40))) || (REG_MCM && REG_BMM)) {	// Multicolor character
 				// using static vars: faster in a rapid loop like this, no need to re-adjust stack pointer all the time to allocate space and this way using constant memory address
 				// also, as an optimization, later, some value can be re-used and not always initialized here, when in reality VIC
 				// registers in current Xemu cannot change within a scanline anyway (ie, scanline precision based emulation/rendering)
@@ -1530,13 +1530,13 @@ static XEMU_INLINE void vic4_render_char_raster ( void )
 					// value 00 is common /w or w/o BMM so not initialized here
 					color_source_mcm[1] = char_value >> 4;	// 01
 					color_source_mcm[2] = char_value & 0xF;	// 10
-					color_source_mcm[3] = color_data & 0xF;	// 11
+					color_source_mcm[3] = (vic_registers[0x63] & 0x40) ? color_data : color_data & 0xF;	// 11
 					char_byte = *(row_data_base_addr + display_row * (LINESTEP_BYTES * 8) + 8 * line_char_index + sel_char_row);
 				} else {
 					// value 00 is common /w or w/o BMM so not initialized here
 					color_source_mcm[1] = REG_MULTICOLOR_1;	// 01
 					color_source_mcm[2] = REG_MULTICOLOR_2;	// 10
-					color_source_mcm[3] = color_data & 7;	// 11
+					color_source_mcm[3] = (vic_registers[0x63] & 0x40) ? color_data : color_data & 7;	// 11
 					char_byte = *(row_data_base_addr + (char_id * 8) + sel_char_row);
 				}
 				// FIXME: is this really a thing to have FLIP in bitmap mode AS WELL?!