assorted fixes

A set of assorted fixes to the exercises.

* feature the name of the task in the section header -- that makes it look more important and should thereby reduce the number of people asking for help without specifying which task they were given
    * if that doesn't help, we can add a warning about this at the end of the task descriptions
* fixes to 1b (mastermind)
    * baseline-align the letters in the bytefield boxes -- no more _p_ flying in the air
    * use the v2 bytefield interface (changes to the endianness specification method)
    * assorted formatting/grammar/style fixes
* fix a few formatting details I missed last time
* explicitly add paragraph breaks to the definition of _osuefmtcode_ -- otherwise, TeX places the minipage right next to the text, which might confuse later users of the template