nxstyle improvements with No tooling (#12)

tools/nxstyle.c:  Output compiler like error format.  Added features

   Uses getops to pars command line.
   Supports
      -s silence all output
      -g provide a PASS fail message

* tools/README.txt:  Update with new nxstyle options

tools/README.txt

@@ -313,7 +313,15 @@ nxstyle.c
   standard.  This program is completely ignorant of C syntax; it simply
   performs crude pattern matching to check the file.
 
-  Usage: nxstyle <path-to-file-to-check>
+  Prints formatted messages that are classified as info, warn, error, 
+  fatal. In a parsable format that can be used by editors and IDEs.
+
+  Usage: nxstyle [-m <maxline>] [-v <level>] <filename>
+        nxstyle -h this help
+        nxstyle -v <level> where level is
+                   0 - no output
+                   1 - PASS/FAIL
+                   2 - output each line (default)
 
   See also indent.sh and uncrustify.cfg