Fix M49 so that it does not hang the terminal console.

Remove duplicates, with followup fixes

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

Travis fix - only allow ultralcd_st7920_u8glib_rrd_AVR.cpp to compile when ST7920 selected

Travis is having problems at:  https://github.com/MarlinFirmware/Marlin/pull/8560   

So...   doing a direct commit to get things correct.   Bugfix_v1.1.x does not have this bug.  Nothing needs to be done to that branch.