[Swift] Syntax error in antlr4/runtime/Swift/boot.py
[Swift] Syntax error in antlr4/runtime/Swift/boot.py

Make boot.py work under both Python 2 and 3.  This fixes #2369.

Add an extra exception handler, for neater error messages.

ericvergnaud/antlr4,parrt/antlr4,ericvergnaud/antlr4,antlr/antlr4,ericvergnaud/antlr4,antlr/antlr4,parrt/antlr4,ericvergnaud/antlr4,antlr/antlr4,ericvergnaud/antlr4,antlr/antlr4,ericvergnaud/antlr4,antlr/antlr4,ericvergnaud/antlr4,parrt/antlr4,antlr/antlr4,antlr/antlr4,antlr/antlr4,parrt/antlr4,parrt/antlr4,antlr/antlr4,parrt/antlr4,ericvergnaud/antlr4,parrt/antlr4,antlr/antlr4,parrt/antlr4,ericvergnaud/antlr4,parrt/antlr4,ericvergnaud/antlr4,parrt/antlr4