Parse column/position information from javac error messages

[vasilmkd]

Resolves #1372 .

I've made a binary incompatible change to sbt.internal.inc.javac.JavaPosition. What is the binary compatibility guarantee of this package, given that it has internal in the name?

I can re-add the old constructor to preserve binary compatibility. However, even if I add the constructor once more, one of its parameters is no longer uses in the same way as it was before.

Any advice or preference on this matter is appreciated.