Test suite for operations on primitives

Test includes:
 - `!`, `==`, `!=`, `<`, `>`, `<=`, `>=` on Booleans,
 - `||`, `&&`, `&`, `|`, `^` on Booleans,
 - `+`, `-`, `*`, `/`, `%` on numerics,
 - bitwise `&`, `|`, `<<`, `>>`, `>>>`, `^` on integrals,
 - unary `+`, `-` on numerics and unary `~` on integrals,
 - type conversion (`toXXX`)
 - and various other methods defined in `ScalaNumberProxy`,
   `RichXXX`, `Fractional` and `Integral`.

This test suite was extracted from previous commit to ease review process.
Implementation of conditional breakpoints

Based on expression evaluator.
User interface for expression evaluator

Complete with history command, tree view for values, simple content
proposal and multiple configuration parameters.
RunSelectionInInterpreter action added

Runs currently selected text in expression evaluator view.
AUTHORS file updated with names of expression evaluator authors