SCON grammar enhancements

- End of line comments start with '#'
- Include file syntax is '$include "filename"' or '$include{"filename"}'

Examples are shown below:

test {
  key1 = "value1"            # This is a comment
  key2 = true                # Supported value types: str | int | double | bool

  key3   value3              # Equal sign is optional as well as double quotes
                             #   (in the absence of double quotes the data type
                             #    is inferred. Strings with spaces and special
                             #    characters have to be double quoted)

  key4 = 4, key5 = 5.0       # Key/value pairs can be separated by ','

  key6 = test1,              # Keys don't have to be unique
  key6 = test2,              # and before end of line keys can be comma-delimited

  key7 {                     # Keys can have unlimited hierarchy of child nodes
    key71 = true
    key72 = value72 {
      key721 = 100,
      key722 = 1.0
    }
  }

  key8{k1=1,k2=2}            # Some
  key9=value9{k1=1,k2=2}     #      more
  key9 value9{k1=1,k2=2}     #           examples

  key10 value10 {            # Child nodes can have values (e.g. "address")
    key101 = true            # Supported value types: str | int | double | bool
    $include "name.conf"     # Supports inclusion of other files at any level
  }

  $include{file=name.conf,
           root=/logger  }   # Include directive may specify that not the
                             # whole file needs to be included, but only the
                             # part matching the path

  # Valid include syntax:

  $include "filename"
  $include="filename"
  $include { "filename" }
  $include "filename" { root = "path.to.root.node" }
}
Work in progress