Lots of spelling, grammar, diction, and punctuation fixes to en_US

* Consistently changed the tense of research notes from past tense to
  past perfect tense to be in line with Thaumcraft notes

* Even though this says en_US, it uses a number of British spellings
  (e.g., mould, colour, labour). I've left them in, uncorrected. Words
  like "analyze", "armor", etc. are correctly en_US, however.

* Made some minor tweaks to the flavor text to make it less bland.

* Changed "of Withhold" to "of Withholding". Corrected "desintigrate"
  to "disintigrate". These are the only changes to item names.

Take all of it as suggestions.