use underscore instead of dash to make rpmbuild happy
cleanup configure --help

All options should now use AC_HELP_STRING, and help texts should
start with a lowercase letter.
minimal cleanup of configure.ac

move SQLITE3 conditional definition before needsqlite3 test,
fix unixodbc detection message.
upgrade boost.m4

fixes scary warning from configure:
    checking for the toolset name used by Boost for g++... configure: WARNING: could not figure out which toolset name to use for g++
make webserver HTML valid
restyle builtin webserver page

should closely match the powerdns CI, except for the font.
Merge pull request #760 from zeha/f/inbox-html

restyle builtin webserver page - many thanks to ch and mind04!
Merge pull request #759 from zeha/f/upgrade-boost-m4

upgrade boost.m4
Merge pull request #757 from zeha/f/configure-help

cleanup configure