[observer] Fix non tail-recusive loop when measuring scheduler utilization
[observer] Improve measurement of CPU utilization in etop

Now using scheduler_wall_time instead of runtime/wall_clock to get cpu
utilization. The old version could give CPU utilization far beyond 100%.

Also, a bug which sometimes gave a badarith when calculating the CPU
utilization is corrected.
Use erlang:demonitor(Ref, [flush]) where applicable
Encode Erlang source files with non-ascii characters in UTF-8

To ensure that 'master' compiles when we merge 'maint' to it,
regardless of which encoding is default in 'master', all source
files with non-ascii characters *must* have the encoding specified.
Merge branch 'bjorn/fix-encoding/OTP-11041' into maint

* bjorn/fix-encoding/OTP-11041:
  Encode Erlang source files with non-ascii characters in UTF-8
Remove the "coding: utf-8" comment from all Erlang source files
Convert XML files to UTF-8, where needed
Convert XML files to UTF-8
observer: Add allocator info to gui
observer: Improve initial call info
Merge branch 'maint'