KT-1237 Auto-completion of "return" keyword should not insert space after it when in a method returning Unit

 #KT-1237 fixed
 #KT-1238 fixed

Holds reference to runtime.jar and jdk-headers.jar. Paths to these
jars are no longer hardcoded.

Many tests now compile runtime before execution. Because of this:
* Single test invocation is significantly slower now for some tests
* This can be fixed by making tests independent from runtime (this
must be done anyway)

Some tests still depend on runtime.jar built by "ant dist", this
is to be fixed.

(will be used later)

 #KT-1137 fixed

... and compute "kotlin" flag in ResolverScopeData

 #KT-1666 fixed

Implemented better rendering for parameters with default values in decompiler and descriptor renderer.

 #KT-1582 fixed

 #EA-35266 fixed

 #KT-1676 fixed

include jdk-headers, do not include runtime

unfortunately I couldn't write test that proves this code is wrong