Add AUTHORS and .gitignore

.gitignore

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+*~
+*.dSYM
+.DS_Store

AUTHORS

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+Ian Piumarta (2016-)
+	infrastructure
+	parsing framework
+	C grammar, C AST
+	object system design and implementation
+	metalanguage design and implementation
+
+Mahe Tardy (2020)
+	object system implementation
+	metalanguage implementation
+
+Nathan Razafimanantsoa, Kumar Mahadayya (2021)
+	C AST