[ruby-core:17200] miniunit to replace test/unit in 1.9(?)

Koichi asked me to double-check with Matz and ruby-core that it is OK  
to replace test/unit with miniunit in 1.9. I last proposed this in  
November [ruby-core:13586] and it was approved by Akira pending  
changes to make it more compatible (at the time it was young).

---

I'm pushing to get miniunit flushed out and replacing test/unit by the  
16th. I've been using it as a full replacement for several weeks now,  
but my work/code habits are very consistent so I might be missing  
something. I've released the latest version of the code to get user  
feedback from as many people as possible before the 16th. Let me know  
if you'd prefer I didn't make this change for this release.

I proposed replacing it with miniunit, which is 100% compatible on the  
test side (but not on the runner side). I've released test/unit as a  
gem in its current form for tool vendors who need runner compatibility  
(think komodo IDE and other similar development environments).

I will ensure that any tests in ruby's test suite that use test/unit  
internals in an incompatible way are modified to work with miniunit.

One additional thing I should point out is that miniunit is MUCH MUCH  
cleaner and more maintainable than test/unit, yet increases the number  
of assertions and adds mini/spec (an rspec-like extension) and mini/ 
mock (a very clean and simple mock framework). Providing spec and mock  
extensions round out the functionality quite nicely and allow people  
to test however they work best.

Check out the line count and complexity differences:

miniunit

   lib  loc     646 total
   test loc     905 total
   totl loc    1551 total
   flog = 711.105369946191

test/unit

   lib  loc    3571 total
   test loc    2464 total
   totl loc    6035 total
   flog = 3103.27739878118