[Issue 447] frontend: writeable string constants

[Walter Bright]

Walter Bright wrote:
> My bugs tend to be cases I hadn't thought of, i.e. unexpected 
> interactions between features.

I want to add that, in my experience, the single most important 
contributor to producing a bug-free product is a thorough test suite. 
Yours has proven its worth over and over, and is doing so again in 
helping proof the 64 bit GDC.

The best tool to help create a test suite is a coverage analyzer, like 
-cov for DMD and -gcov for gcc. I'm guilty of not using them enough, but 
their worth is beyond dispute.

The other way to create a test suite is to put every bug report into it 
after it's fixed. That one I do do diligently, and you do too.