This commit introduces the ability to specify an inline map in
an expression. The syntax is similar to inline lists and of
the form: "{key:value,key2:value}". The keys can optionally
be quoted. The documentation is also updated with information
on the syntax.

Issue: SPR-9472

There is special handling for SpEL expressions involving a map
and an unquoted string literal key (e.g. mymap[key1]). SpEL does
not require key1 to be quoted. This special handling which is done
in Indexer getValueRef() was not being also done in the Indexer
generateCode() method that compiles the expression. Also fixed
a problem where the key was not being compiled in a new
sub scope. Without the new scope the key expression was failing
to reload the relevant context object when it needed it.

Issue: SPR-12045

This commit enables the modulus operator to be compiled when
it is used as part of a SpEL expression.

Issue: SPR-12041

This commit allows the SpEL compiler to cope with generic methods
being used in expressions involving numeric operands. Due to the
use of unbound type variables the methods may look like they
return Object but in fact they are returning objects of a numeric
type that are suitable for compilation. The changes here ensure
the runtime types are looked at if the discovered declared types
are not providing enough information. This impacts all the
operands involving numerics (mathematical and relational).

Issue: SPR-12040

Issue: SPR-12014

Revision of SpelCompiler support, resolving a subpackage cycle through moving CodeFlow and CompilablePropertyAccessor to the main spel package

Also contains explicit ClassLoader management, passed through StandardBeanExpressionResolver and SpelParserConfiguration to SpelCompiler lookup.

Issue: SPR-10943

With these changes an optional compiler is added for SpEL
expressions. The compiler is off by default but can be enabled
via the SpEL parser configuration object or system property
(when SpEL is embedded and parser configuration is not possible).
Not all expressions are currently handled but the common
cases are and it is an extensible compilation framework.

Issue: SPR-10943

Issue: SPR-11960

Issue: SPR-11721
(cherry picked from commit 59cef3ce)

Clean up compiler warnings in the tests of spring-expression. This
commit adds type parameters to some of the types (mostly `List` and
`Map`). Some of them can't be cleaned up, some tests are even
specifically for raw types.

Issue: SPR-11708

Issue: SPR-11609

Prior to this commit, the codebase was using a mix of log4j.xml
and log4j.properties for test-related logging configuration. This
can be an issue as log4j takes the xml variant first when looking
for a default bootstrap configuration.

In practice, some modules declaring the properties variant were
taking the xml variant configuration from another module.

The general structure of the configuration has also been
harmonized to provide a standard console output as well as an
easy way to enable trace logs for the current module.

Issue: SPR-11535
(cherry picked from commit eeb82c40)

 When a node of an SPeL expression was a call to a bean referenced
 in a method argument, the expression was resolved twice.

 The resolved arguments are now specified to MethodValueRef instead
 of resolving the arguments again in the constructor

 Issue: SPR-11445

Fixed through falling back to the raw parameter type in the TypeDescriptor(MethodParameter) constructor, properly detecting the vararg array even in case of an unresolvable type variable, and through restoring getElementTypeDescriptor's original behavior for arrays, i.e. always returning a non-null descriptor.

Issue: SPR-11494

Add additional caching to ResolvableTypes and SerializableTypeWrapper
in order to improve SpEL performance.

Issue: SPR-11388

- Consistent importing of org.junit.Assert.*;
- Proper declaration of expected exceptions via @test(expected).
- Renamed SpEL ExpressionTestCase to AbstractExpressionTests.
- Formatting and test method naming conventions.

Issue: SPR-11348

Issue: SPR-11319

Fixed getTypeDifferenceWeight algorithm in ReflectionHelper, and removed unused argsRequiringConversion storage

Issue: SPR-11306

Issue: SPR-7831

Issue: SPR-11215

Issue: SPR-11215

Fix regression introduced in b25e91a5 where ReflectivePropertyAccessor
does not consider the return type for "is" getters.

Issue: SPR-11142

Update code to have a consistent number of new-line characters after
import statements.