Stop using quasiquotes in Simple.hs

For some reason this was causing haddock to fail.   This may be a bug
in cabal-install or ghci and is worth further investigation at some point.
For example

$ cabal haddock
Running Haddock for postgresql-simple-0.3.0.0...
Warning: The documentation for the following packages are not installed. No
links will be generated to these packages: rts-1.0
Preprocessing library postgresql-simple-0.3.0.0...
Haddock coverage:
   2% (  1 / 49) in 'Database.PostgreSQL.Simple.TypeInfo'
   8% (  4 / 50) in 'Database.PostgreSQL.Simple.Time.Implementation'
   9% (  1 / 11) in 'Database.PostgreSQL.Simple.Time.Internal'
   4% (  1 / 26) in 'Database.PostgreSQL.Simple.Time'
  80% (  8 / 10) in 'Database.PostgreSQL.Simple.Arrays'
 100% (  2 /  2) in 'Database.PostgreSQL.Simple.SqlQQ'
  88% (  7 /  8) in 'Database.PostgreSQL.Simple.Types'
 100% (  4 /  4) in 'Database.PostgreSQL.Simple.ToField'
 100% (  2 /  2) in 'Database.PostgreSQL.Simple.ToRow'
  67% (  2 /  3) in 'Database.PostgreSQL.Simple.Ok'

dist/build/tmp-15448/src/Database/PostgreSQL/Simple/Internal.hs:44:1:
    Warning: The import of `System.IO.Unsafe' is redundant
               except perhaps to import instances from `System.IO.Unsafe'
             To import instances alone, use: import System.IO.Unsafe()
  38% (  9 / 24) in 'Database.PostgreSQL.Simple.Internal'
  22% (  4 / 18) in 'Database.PostgreSQL.Simple.LargeObjects'
  75% (  3 /  4) in 'Database.PostgreSQL.Simple.Notification'
  80% (  4 /  5) in 'Database.PostgreSQL.Simple.Errors'
 100% (  3 /  3) in 'Database.PostgreSQL.Simple.Compat'
  17% (  1 /  6) in 'Database.PostgreSQL.Simple.BuiltinTypes'
  79% ( 11 / 14) in 'Database.PostgreSQL.Simple.FromField'
  33% (  2 /  6) in 'Database.PostgreSQL.Simple.FromRow'

ByteCodeLink.lookupCE
During interactive linking, GHCi couldn't find the following symbol:
  postgresqlzmsimplezm0zi3zi0zi0_DatabaseziPostgreSQLziSimpleziSqlQQ_sql_closure
This may be due to you not asking GHCi to load extra object files,
archives or DLLs needed by your current session.  Restart GHCi, specifying
the missing library using the -L/path/to/object/dir and -lmissinglibname
flags, or simply by naming the relevant files on the GHCi command line.
Alternatively, this link failure might indicate a bug in GHCi.
If you suspect the latter, please send a bug report to:
  glasgow-haskell-bugs@haskell.org
Remove an unused import
Refactor conversion function

This gets rid of an (incorrect) warning message, eliminates some
dead code in the generated code,  and keeps things under 80 characters
Major reorganization
Add Conversion monad
Move FromField and FromRow to new Conversion monad
Stop pre-calculating typeinfos
Stop exporting some of the more detailed transaction options
Make typeinfo part of public FromField API
Add overview and example code to FromField
Tweak documentation