Always unlock the same session instance that was locked (#12481)

Change-Id: I15ff1177d827bc8fee9f8f723f9a288b0c3aea71
Avoid leaking memory from inherited ThreadLocales. Fixes #12401

The issue is fixed by changing the normal HashMap inside the inheritable
thread local to a map implementation holding only weak references to the
values (WeakValueMap).

Also included is a test UI that starts threads, which run until the JVM
is quit. This along with VisualVM was used to reproduce the issue and
verify the fix.

Change-Id: I116cc4e56e8a19c3b770abab6b18b9e262f4dafa
Updated _trackMessageSize based on latest upstream version (#12468)

Change-Id: Ie7db27a026d52befe027ed2abb96e62947f8116d
Table ignores Container updates while painting (#12258)

Vaadin threw an IllegalStateException if a Container was updated while
Table was being painted. SQLContainer was known to invalidate its cached
size during a Table repaint, resulting in an ItemSetChangeEvent. This fix
has been copied over from how ComboBox handles this situation.

Change-Id: I04af71a5ea3844da245cb9e31ada4a30ff704619
The colon in the calendar event caption is now also hideable. Fixes #12460

Change-Id: Idc81c3cc614bc59c2a93615bd5ac5cac9b72f752
Corrected typo in version variable (#12440)

Change-Id: Ib9a3efee02f4887072e7892d869911b78ec5e1d8
Changed 'feature release' text to maintenance release (#12486)

Change-Id: I2896136065232d2704bb4807ff92e6ef384407e8
Updated browser versions

Change-Id: If091d718fc45b226a60a4c69d3469b4b31919ac1
Fix regression where empty RTA returns <br> (#12490)

Change-Id: I273037644ed1383af84898cf03360e2b08d2647b
Add deprecation message to unused constant

Change-Id: Ifcc4e021fa3843129f6501d6526e4d4f5c6930fb
Sets the locale in the test case. #12460

TestHideTimeAndSeparator didn't specify a locale, which
caused it to fail if the locale on the system where it
ran was different from the one on the system where the
test was created.

Change-Id: I44de92c68954eac425308eeaf7e07e76c717f2bf
Excludes WeakValueMap from the serializable test #12401

Also added a note to the WeakValueMap JavaDoc stating that it is
not serializable.

Change-Id: If342746ad7c7cac0db8bac4ba75236970cc4cd01
Merge changes from origin/7.1

d8b0b50 Always unlock the same session instance that was locked (#12481)
e6af0f0 Avoid leaking memory from inherited ThreadLocales. Fixes #12401
f7ee8fb Updated _trackMessageSize based on latest upstream version (#12468)
a24d391 Table ignores Container updates while painting (#12258)
7068d78 The colon in the calendar event caption is now also hideable. Fixes #12460
61dd8f7 Corrected typo in version variable (#12440)
476e0b8 Changed 'feature release' text to maintenance release (#12486)
faa2569 Updated browser versions
831747a Fix regression where empty RTA returns <br> (#12490)
cb8df75 Add deprecation message to unused constant
4c5bb0e Sets the locale in the test case. #12460
11cdf93 Excludes WeakValueMap from the serializable test #12401

Change-Id: Id7eeba06d14518c254ceb01e38e2441967932755