Add make setup-antlr

Makefile

@@ -3,7 +3,7 @@ default: build
 all: go test grammar-java
 build: go
 
-algorand-link:	
+algorand-link:
 	SYM_DIR_LOC=$$(go env GOPATH)/pkg/mod/$$(echo $$(grep -F 'github.com/algorand/go-algorand' go.mod | sed 's/ /@/' | cut -d " " -f1 )) ; \
 	SYM_DIR_TARG=$$(go env GOPATH)/src/github.com/algorand/go-algorand; \
 	[ ! -d "$$SYM_DIR_TARG" ] && echo "error: target directory not found ($$SYM_DIR_TARG)" && exit 1; \
@@ -12,7 +12,12 @@ algorand-link:
 	echo "targ=$$SYM_DIR_TARG" "linkloc=$$SYM_DIR_LOC"; \
 	ln -s "$$SYM_DIR_TARG" "$$SYM_DIR_LOC"
 
-ANTLR4_JAR := /usr/local/lib/antlr-4.9.2-complete.jar
+ANTLR4_VER := 4.9.3
+ANTLR4_JAR := /usr/local/lib/antlr-$(ANTLR4_VER)-complete.jar
+
+setup-antlr:
+	sudo curl -o $(ANTLR4_JAR) https://www.antlr.org/download/antlr-$(ANTLR4_VER)-complete.jar
+	export CLASSPATH="$(ANTLR4_JAR):$$CLASSPATH"
 
 grammar-all: grammar-go
 

README.md

@@ -97,6 +97,7 @@ Checkout [syntax highlighter](https://github.com/pzbitskiy/tealang-syntax-highli
 ### Prerequisites
 
 1. Set up **ANTLR4** as explained in [the documentation](https://www.antlr.org/)
+   Or run `make setup-antlr`
 2. Install runtime for Go
     ```sh
     go get -u github.com/antlr/antlr4/runtime/Go/antlr