add test for formatting commands

tools/format_test.txt

@@ -0,0 +1,5 @@
+Nor
+\uUnderline\u\u
+\bBold\b
+\k\k\k\k\k\k   mal
+\j\j\j\j

tools/printfile.py

@@ -47,7 +47,7 @@ def main():
     lines=[x.rstrip() for x in lines] # remove whitespaces and linebreaks
     
     for iline,line in enumerate(lines):
-        if not set(line).issubset(chars):
+        if not set(line).issubset(chars+'\\'): 
             print(str(iline)+":"+str(line))
             print("Contains non printable characters")
             exit()