replace '$' (which is not usable at the start of line) by 'C ' for functionnal comment

Author: yannrichet

README.md

@@ -10,7 +10,7 @@ It supports the following syntax and features:
     * parameter syntax: 
       * variable syntax: `%(...)`
       * formula syntax: `@{...}`
-      * comment char: `$`
+      * comment char: `C ` (note that it holds two chars)
     * example input file:
         ```
         Godiva-type critical reactor and kcode example

src/main/io/MCNP.ioplugin

@@ -3,7 +3,7 @@ variableLimit=(...)
 formulaStartSymbol=@
 formulaLimit={...}
 
-commentLineChar=$
+commentLineChar=C 
 
 datasetFilter=contains("(.*)","KCODE") || contains("(.*)","kcode")