Add support for var variable declarations

[Drodt]

Intended Change

Allows parsing of declarations with type inference, e.g.:

var x = 0;

These declarations are converted to declarations with explicit types. The declaration above is translated to

int x = 0;

This change required adding the Java10PostProcessor to our JavaParser instances. No additional taclets are necessary.

Type of pull request

• New feature (non-breaking change which adds functionality)
• There are changes to the (Java) code

Ensuring quality

• I made sure that introduced/changed code is well documented (javadoc and inline comments).
• I made sure that new/changed end-user features are well documented (https://github.com/KeYProject/key-docs).
• I added new test case(s) for new functionality.

Additional information and contact(s)

The contributions within this pull request are licensed under GPLv2 (only) for inclusion in KeY.

[wadoon]

Did you also test it with referenced types? Parameterized types are currently out of reach.

The hardest thing should be: var x = b ? new String() : 2

[Drodt]

That example leads to an UnsupportedOperationException in JavaParser.