database: two new columns

Added sectionID to define where the topic is to be found in, and
is_sticky with three different levels (0, 1, 2).
0 defines no sticky mode, 1 defines low sticky mode and 2 defines high
sticky mode.
index: moved page handling into theme

Will be rewritten anyways later on. Just need it for testing.
theme: added topic listing and a few checks

Also added the page handling into the theme temporarily.