[test_server,common_test] Fix cross cover mechansim

Update the interface for cross cover analysis (collection of cover
data over multiple tests) so it can be used via common_test and
directly with test server.

The concept of 'application' in the cross cover interface is removed
and replaced with an arbitrary Tag=atom() which identifies a test run.
[test_server] Add test of code cover mechanism
[test_server] Update documentation about cross cover

Add info about cross statement in cover file:
{cross,[{Tag,Modules}]}.

Add parameter Tests = [{Tag,Dir}] to test_server_ctrl:cross_cover_analyse
[test_server] Don't use print/3 in cross_cover_analyse

Cross cover analysis is executed outside the scope of
test_server_ctrl, i.e. test_server_ctrl is not necessarily
started. This may cause test_server_ctrl:print/3 to hang. Instead use
io:fwrite directly (as it was before).
[test_server] Stop cover on node after node is terminated

Before terminating slave nodes, test_server calls cover:flush/1 to
fetch data from the node without actually stopping cover on this
node. If cover is not stopped for the node and a new node with the
same name is started, then cover will be started on the new node. To
avoid this test_server now calls cover:stop/1 after the slave node is
terminated.
[test_server] Add Unicode support to module listing

Code written by Siri Hansen.
Merge branch 'siri/cover/new-bugs-r16/OTP-10638'

* siri/cover/new-bugs-r16/OTP-10638:
  [cover] Cleanup by stopping cover between tests
  [common_test] Stop cover on slave node after node is terminated
  [test_server] Stop cover on node after node is terminated
  [cover] Fix timing dependent bug in cover_SUITE:reconnect
  [cover] Remove stopped node also from lost_nodes list
  [cover] Don't mark stopped node as lost
test_server: Remove support for packages
Merge branch 'siri/cross-cover/OTP-9870'

* siri/cross-cover/OTP-9870:
  [test_server] Don't use print/3 in cross_cover_analyse
  [common_test] Add documentation for cross cover analysis
  [common_test] Add test case for cross cover mechanism
  [test_server] Update documentation about cross cover
  [test_server] Add test of code cover mechanism
  [test_server,common_test] Fix cross cover mechansim
Implement ./otp_build configure --enable-silent-rules

With silent rules, the output of make is less verbose and compilation
warnings are easier to spot. Silent rules are disabled by default and
can be disabled or enabled at will by make V=0 and make V=1.
Remove what remains of the Mnemosyne code
Merge branch 'nox/enable-silent-rules/OTP-10726'

* nox/enable-silent-rules/OTP-10726:
  Implement ./otp_build configure --enable-silent-rules
Merge branch 'lh/forget-mnemosyne/OTP-10729'

* lh/forget-mnemosyne/OTP-10729:
  Remove what remains of the Mnemosyne code
  Remove support for the query keyword and query expressions
Turn warnings to errors on selected applications
[test_server] Fix copyright in erl2html2_SUITE.erl
[test_server] Update test_server to handle unicode

* Use UTF-8 encoding for all HTML files, except the HTML version of
  the test suite generated with erl2html2:convert, which will have the
  same encoding as the original test suite (.erl) file.

* Encode link targets in HTML files, allowing both special characters
  like "/", "&", "?" etc, and latin1 or unicode characters.

* Use unicode modifier 't' with ~s and ~p when appropriate.

* Use unicode:characters_to_list and unicode:characters_to_binary for
  conversion between binaries and strings instead of binary_to_list
  and list_to_binary.
[test_server] Write link target with correct encoding in erl2html2

If the encoding of the source file was utf-8, then the link target
could be faulty encoded in the resulting HTML file. This has been
corrected.
[test_server] Add tests for unicode support
[ts] Use unicode:characters_to_list/2 instead of binary_to_list/1

When reading text files with file:read_file/1, assume that the file
has the default encding (epp:default_encoding()) and covert the binary
to string by unicode:characters_to_list(Bin,DefaultEncoding) instead
of binary_to_list(Bin) as before.
[test_server] Ensure correct encoding in header for erl2html2:convert

When running under framework common_test, the encoding statement in
the HTML header of the file generated with erl2html2:convert would
sometimes be faulty. This has been corrected.