Fix "language" typo.
Add cache table for team totals for efficiently computing team rank. This is not used anywhere yet.
Use smart rank computation for displaying team row. This can highly improve efficiency in contests with many teams, but the behavior is not completely unchanged. There are two changes:

* The first correct submission per problem is not computed, so the dark-green cells in the table for first-correct per problem are not shown on the team page.
* When a problem for which there are correct submissions is disabled during a contest, the cache is out-of-sync and should be rebuild.
Do not try to install no-more-existent lib/ext/ dir.

Leaving the configure variable libextdir for now, since we may want
to reintroduce such a dir in the future.

Thanks Francisco Justo for reporting.
Move test files with backslashes to tarball, since they give
problems on Windows.
Rename SQL tables scoreboard_* to scorecache_* to match new
rankcache_* tables, and make their function clear.
Add changelog.
Reformulate table create query to match SQL dump output.
Add note that maintainer-* make targets replace normal ones.
Put maintainer documentation in more natural order.
Move "declare(ticks = 1)" code to common initsignals() function.
Add configure_input auto-generate string.
Fix indexing over teams and improve layout of array() call.
Fix SQL event insert query and refer to correct alternate
location in case of verification not required.
Rename FIXED_TEAM to FIXED_USER in domserver config.
Partial update to new JSON API specification.
Added support for public sample testcases.

Contestants can view testcases marked as sample as well as their
program output on these cases.

WARNING: this can and will leak information about the problem like
timelimit and more.

Cherry-picked from: 177a655d
Add option to enable teams to see sample testcase run output.
Also clean up rankcache_* tables when refreshing cache.
Update comments for support of HTTP methods, simplify code
and break up some long lines. No functional change.