Add niw to contributors.
Add niw to contributors.

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