Fix: Inconsistent space between console history and current line.

[PeterN]

Motivation / Problem

When there are multiple lines showing in the in-game console, the spacing between the last two lines is less than the spacing between all other lines.

The line height is taller than normal character height, and DrawStringMultiLine() with SA_BOTTOM will draw at the bottom of the line, so the bottom position needs to be adjusted up.

Description

Resolved by adding missing vsep_normal padding to initial bottom position.

Limitations

Checklist for review

Some things are not automated, and forgotten often. This list is a reminder for the reviewers.

• The bug fix is important enough to be backported? (label: 'backport requested')
• This PR touches english.txt or translations? Check the guidelines
• This PR affects the save game format? (label 'savegame upgrade')
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, game_changelog.hpp need updating.
  • The compatibility wrappers (compat_*.nut) need updating.
• This PR affects the NewGRF API? (label 'needs review: NewGRF')
  • newgrf_debug_data.h may need updating.
  • PR must be added to API tracker