added four new tests for string and char[] behaviour

invalid/semanticErr/expressions/stringElemErr.wacc

+# element access is not permitted for strings
+
+# Output:
+# #semantic_error#
+
+# Exit:
+# 200
+
+# Program:
+
+begin
+  string str = "hello world!" ;
+  println str ;
+  str[0] = 'H' ;
+  println str
+end

invalid/semanticErr/print/printTypeErr02.wacc

+# type mismatch: string <- char[]
+
+# Output:
+# #semantic_error#
+
+# Exit:
+# 200
+
+# Program:
+
+begin
+  string s = ['h','i','!'];
+  println s
+end

invalid/syntaxErr/print/printlnCharArry.wacc

+# You cannot directly print a char[] in WACC
+
+# Output:
+# #syntax_error#
+
+# Exit:
+# 100
+
+# Program:
+
+begin
+  println ['H','e','l','l','o',' ','W','o','r','l','d','!']
+end

valid/IO/print/printCharArray.wacc

+# printing the contents of a char[] is possible via an intermediate variable
+
+# Output:
+# hi!
+
+# Exit:
+# 0
+
+# Program:
+
+begin
+  char[] s = ['h','i','!'];
+  println s
+end