Merge branch 'nobigfirst' into 'master'

revert "allocate bigger first"

partial revert of d4fa608 ([L2313](https://gitlab.com/xonotic/netradiant/commit/8bc246a01343d9c9dd3a8b678681710cf04a2953#416ec0c19ddc04c6485e9853a0c8a125f98dca13_2295_2313))
see #54 ([13326399](https://gitlab.com/xonotic/netradiant/issues/54#note_13326399))

"allocate bigger first" change was meant to save allocation time keeping same lightmap file size, actually wastes both time and size

See merge request !32