RCR 207: --freeze commandline option

Introduce a new commandline option that when invoked would freeze all built-in Ruby classes and modules.

Some Ruby users (and potential Ruby users) complain that being able to modify built-in classes and modules is 'dangerous'. Most Ruby users like having the freedom to (carefully) add methods to built-in classes and modules.

Introduce a new commandline argument to the Ruby executable called '--freeze' that would freeze all built-in classes and modules prior to interpreting user code.

This proposal would satisfy both groups of users: those who feel the need for more 'safety' and those who prefer the freedom to add/change methods. Users who do not like changes to internal classes could use the '--freeze' commandline option. It could also be used as an analysis tool to determine if the code being run is making changes to built-in libraries.

if the commandline option '--freeze' is specified on the Ruby commandline, the following code (or equivilent functionality) would be run prior to running the user's script:

  ObjectSpace.each_object(Class) {|c| c.freeze }
 ObjectSpace.each_object(Module) {|m| m.freeze }