move InfoString from ErrorReporting to Decorators and

remove all isSensical/SuppressedMessage logic from InfoString
remove var ContextBase.suppressNonSensicalErrors, and

decouple Diagnostic from ContextBase
add d string interpolator (marks nonsensical error messages)
remove SuppressedMessage exception and update Diagnostic as needed
replace i"..." by d"..." if string might go into a

Diagnostic and might be nonsensical

Conflicts:
	src/dotty/tools/dotc/typer/Checking.scala
	src/dotty/tools/dotc/typer/TypeAssigner.scala
replace some s"..." by i"..."

Conflicts:
	src/dotty/tools/dotc/typer/TypeAssigner.scala
fix: isSensical in d"..." impl must inspect contents of List arg
fix: do not count suppressed messages for summary
Reduce verbosity of logs.

We are already over limit on output size imposed by travis that is shown
in webpage, if we'll continue to add tests will be soon over limit even
to run builds.
This commit disables printing of classpath, and removes printlns in
several places.
In order for ShowClassTests to print info as is was printing
previously, please set "test.ShowClassTests.verbose" property.
Make transforms loggable

using traceIndented in the transform method.
test for allOverriddenSymbols

... to verify whether they work correctly.
Merge pull request #112 from dotty-staging/topic/loggable-transforms

Topic/loggable transforms
Merge pull request #99 from samuelgruetter/infostring2

Error reporting improvements
Merge pull request #110 from DarkDimius/silence

Reduce verbosity of logs.
Install method for SymDenotations

Add a new method to install a SymDenotation after a specific
phase has run. The new denotation replaces the current denotation
of the symbol starting with the period after the given phase.
Bridge generation in erasure implemented.

Relies on meaning of "override" to see which bridges are required.
Doesn't take in account value classes for now
Uses 'adapt' used by erasure for converting arguments and return value.
Merge pull request #109 from DarkDimius/erasure-bridges

Bridge generation in erasure implemented.
Merge pull request #116 from dotty-staging/add/Denotation-update

Install method for SymDenotations
Helper methods for deriving trees.
Symbol.isEffectivelyFinal

Helper method that tests weather this particular
symbol cant have overrides: eg if it's defined in module class,
if it is inner method, if it is method of anonymous class, etc.