Standard Macros

[Speedo]

I'm writing a little library (that contains templates and cpp) that will be compiled by others. 3 of the functionalities I want to provide are:
- Range checking in debug builds
- Include r-value references if available (amongst others)
- add functions if <iostream> is included

I'd really just save yourself the trouble and instead have the user define macros indicating that those features should be used.