[trunk r.3665] Page::isOdd() does not take page offset into account

In file page.h, line 101, the inline function isOdd() returns a wrong value if _score->pageFormat()->_pageOffset is odd.
Among other things, this swaps odd/even page margins, if first page number (menu "Layout | Page layout") is set to an even number.

The function should be moved to file page.cpp and should read:
bool page::isOdd() const
{
return (_no+1 + _score->pageFormat()->_pageOffset) & 1;
}

M.