added labb email contact
added subtitle
updated units information with text from labb
change wording of failed units conversion message
Add page numbers to all pages but 1st

Change implementation of first-page logos from custom header
to ordinary floated-down paragraph.
bugfix: unit conversions incorrect

An extra conversion factor was incorrectly being applied in conversions between
ug/m3 and ppbv.

Changed the unit conversions logic to have explicit definitions of temperature,
pressure, R, molecular weight of air; implemented conversions in terms of
standard formulas.
Merge branch 'capify' into release/production
Merge branch 'capify' into release/production
change comparison description to two-and-a-half, etc.
require password authentication
bugfix: int to str conversion needed
bugfix: ug to mg conversion inverted
Merge branch 'bugfix/over-ten-conversions' into release/beta
limit all reported values to two significant digits
Merge branch 'conversions/match-labb' into release/beta
preserve full precision of user input if input units same as output units
standards: retain original representation if outunits same as standards units
Merge branch 'precision/preserve-user' into release/beta
sort by has-overages, then alphabetically
bugfix: sort order for chemicals