Tabs are now emitted in class definitions.
Fix `IDE.st` that had tabs removed.
Merge pull request #412 from herby/fix-tabs-class-definitions

Fix tabs class definitions
Optimized StringStream >> nextPutAll:

In the 99% of cases, nextPutAll: appends to end of StringStream.
But the whole previous contents for nevertheless copied
at every invocation.
Merge pull request #413 from herby/optimize-stringstream-nextputall

Optimized StringStream >> nextPutAll: