G26 uses logic that looks like:
```
ex = _GET_MESH_X(i + 1) - (SIZE_OF_INTERSECTION_CIRCLES - (SIZE_OF_CROSSHAIRS));
```
The Bi-Linear macros need parenthesis to work correctly.

Fix #8577

Fan speed code fell into a curly brace

During long lasting moves of a delta machine neither the temperatures are maintained nor buttons checked nor ... .
The fix is to call 'manage_heater()' and 'idle()' every now and then in the loop where the move is segmented. 
The code is abot the same as in G2_G3 wher we had the same problem with too large circles lasting too long.
Fixing #7510

Based on #8565

* Initialize mixing virtual tools to behave like standard a multi-extruder setup

* Update Marlin_main.cpp

* Update Marlin_main.cpp

Does it?