・Add new translation

Add symbol-string for _de
to reduce the frquencey of regenerating 'mappers' and 'fonts'
with the new utf-system.

The target here is to update the screens of graphical and char base
displays as fast as possible, without draining the planner buffer too much.

For that measure the time it takes to draw and transfer one
(partial) screen to the display. Build a max. value from that.
Because ther can be large differences, depending on how much the display
updates are interrupted, the max value is decreased by one ms/s. This way
it can shrink again.
On the other side we keep track on how much time it takes to empty the
planner buffer.
Now we draw the next (partial) display update only then, when we do not
drain the planner buffer to much. We draw only when the time in the
buffer is two times larger than a update takes, or the buffer is empty anyway.

When we have begun to draw a screen we do not wait until the next 100ms
time slot comes. We draw the next partial screen as fast as possible, but
give the system a chance to refill the buffers a bit.

When we see, during drawing a screen, the screen contend has changed,
we stop the current draw and begin to draw the new content from the top.

Changes from #5485 by @AndKe

`ftostr62sign()` is used only when displaing/editing
Steps/mm. A sign is not needed - the value is always positive.
Because the number part is long there is no't much place for the values name.
With this PR the is one more char for the name possible.

The non utf8 version of turkish is a bit unhandy.

Delete `language_tr.h`
Rename `language_tr_utf.h` to `language_tr.h`
Provide a propper utf8-mapper for Turkish and use it.

`block_buffer_runtime_us` is mangled in the planner and in the stepper-ISR.
So it needs to be volatile and interrupt protected.