Add first draft of IDEA code formatting

This commit provides a first attempt at defining a standard code
formatting scheme for the Spring Framework in Intellij IDEA.

These are the major changes compared to standard settings:

* default indent option to use tab character instead of space for
  all languages
* one space before the left brace of an array initializer
* keep when reformating: multiple expressions in one line,
  simple blocks in one line
* method declaration parameters: do not align when multiline
* else, catch and finally on new line
* keep one space before } (solely use to keep the space between the
  end of the last method and the end of the class)
* minimum blank line after class header 0 (instead of 1)
* Disabled Javadoc formatting
* class count to trigger static import to 50 (to prevent
  import org.foo.*; instead of listing the classes of org.foo)
* changed the import sequence to import in the following order:
  static imports, java.*, javax.*, others, org.springframework.*. Each
  sequence is separated by a space
Update copyright date in reference manual
Update links to Spring JIRA server
Update author list in reference manual
SPR11348 test should use LinkedHashSet since it relies on insertion order of elements
CollectionToCollectionConverter avoids collection copy for untyped collection when simply returning source anyway

Also uses addAll instead of iteration over untyped collection now, supporting optimized addAll in target collection type, and avoids repeated getElementTypeDescriptor calls.

Issue: SPR-11479
Fix custom config with older HttpClient

Since HttpClient 4.3, custom configuration such as the connection
timeout and the socket timeout are set in a RequestConfig object
stored in the HttpContext.

Unfortunately, older HttpClients are not supporting this
infrastructure and new clients throw an exception when the
deprecated API is used.

This commit detects if the client is an "old" implementation and
set the configuration through the deprecated means to restore
full backward compatibility with these features.

Issue: SPR-11442
Improved documentation on how to convert collections with ConversionService

Issue: SPR-11432
Polishing

Issue: SPR-11442
Tighten connection management in STOMP broker relay

Fix NPE exception when closing TcpConnection

Ensure a ConnectionHandler is cleared when a TcpConnection is closed
(at the same time), logging an exception if the closing fails.

Improve error messages.

Issue: SPR-11531
Add messages for number of active sessions/connections

Issue: SPR-11531
Handle invalid STOMP content-length header value

After this change if a content-length header is provided but is less
than 0 or cannot be parsed as a number, it is ignored and the body
is read sequentially, i.e. until we reach a null byte terminator.

This provides better protection against clients that may set the
content-length header in error.

Issue: SPR-11528
SpEL property-not-found message hints at non-public method/field

Issue: SPR-11535
(cherry picked from commit eeb82c4)
Upgraded to Apache HttpClient 4.3.3 and Jetty 9.1.3
Fix "relay-port" XSD type in spring-websocket.xsd
Prior to this commit, the `relay-port` attribute of the
`<websocket:stomp-broker-relay />` tag was of type `xsd:int`.
This prevents developers from using `PropertyPlaceholderConfigurer`,
even though this configuration key is a good candidate for such use
(this value depends on prod/staging/etc environment).

This commit changes that type to `xsd:string`.

Issue: SPR-11537
Polishing
Improve suffix pattern check

After this change dots inside URI variables in a request mapping
pattern are ignored and no longer considered an indication that
the pattern contains a suffix itself.

Issue: SPR-11532
Fix expected and actual argument order

Issue: SPR-11424
Add HTTP series check shortcut methods to HttpStatus

Issue: SPR-11424
Support multi-line comments in SQL scripts

Prior to this commit neither ResourceDatabasePopulator nor
JdbcTestUtils properly supported multi-line comments (e.g., /* ... */).
Secondarily there has developed a significant amount of code
duplication in these two classes that has led to maintenance issues
over the years.

This commit addresses these issues as follows:

 - Common code has been extracted from ResourceDatabasePopulator and
   JdbcTestUtils and moved to a new ScriptUtils class in the
   spring-jdbc module.

 - Relevant test cases have been migrated from JdbcTestUtilsTests to
   ScriptUtilsTests.

 - ScriptUtils.splitSqlScript() has been modified to ignore multi-line
   comments in scripts during processing.

 - ResourceDatabasePopulator supports configuration of the start and end
   delimiters for multi-line (block) comments.

 - A new test case was added to ScriptUtilsTests for the new multi-line
   comment support.

Issue: SPR-9531