Move to beginning of line before indent

If we don't go to the start of the line before checking what kind of
indentation we need we will be calculating a possible different
indentation value depending on the location of `point'.
Don't recalculate default each time

Recalculating the default value each time causes it to be used for the
wrong situations. `sgml-mode' should calculate the value once, and if
it is decided that `pony-mode' won't indent it that value should be
used. At the time of that decision the point could be many lines
higher and a different indentation may be appropriate there.
Merge pull request #72 from ryuslash/indent-fix

Indent fix