Make MAPPER_NON the fall back mapper - if no other is defined.
One list less to maintain.

New strings:
#define MSG_HALTED
#define MSG_PLEASE_RESET
Some texts shortened for smaller displays.

In all these cases we want the axis to be homed. If we could have lost
some steps is secondary.

Reenables homing seperate axis with DISABLE_X / DISABLE_Y true.

Following up on #3231

documentation/LCDLanguageFont.md moved to http://www.marlinfirmware.org/ at commit 12d0983757,
but http://www.marlinfirmware.org/ isn't working.

Czech language translation.