Verify the current implementation of UCUM and bring comments up-to-date

[magnonasc]

The UCUM version being used on this implementation is 1.9, and as UCUM is on its 2.0.1 version there is a need to check for changes and fix the comments with missing sections (e.g., TYPESETTER'S LENGTH UNITS: UCUM 4.4 §39 which now is §42) to make it easier to look for them on UCUM documentation when working on #59.

[magnonasc]

In public static final Unit<Action> PLANCK = addUnit(SI.JOULE_SECOND.multiply(6.6260755E-24)); //FIXME get rid of JXQ import (where from??) on UCUM class, how does this error relates to the wrong value that should be 6.6260755E-34 instead of 6.6260755E-24? Or where you referring to something else? It seems that the build is still okay after fixing that, what makes me confused about your comment.

[keilw]

I cannot exactly point JXQ to anything still in the current code. It may have been from JScience or an earlier codebase. Should be safe to drop the comment.

[magnonasc]

Okay, so I'll just fix the wrong value and drop the comment... Feel free to assign this issue to me as I'm working on it already.

[magnonasc]

Just some typos and two errors were found as part of this issue, the others are just missing and might be added as part of #59.