Codechange: Use dynamic string list for contents of land info window.

[michicc]

Motivation / Problem

Land info window is using a fixed char array for storing the window's contents. As a safety margin to account for any possibilities, the buffer is a lot larger than the typical contents needs.

Description

Instead of the fixed array that is larger than needed, store the text in a dynamic StringList. While we're at it, remove the remaining c-style string bits.

Limitations

None.

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 affects the save game format? (label 'savegame upgrade')
• This PR affects the GS/AI API? (label 'needs review: Script API')
  • ai_changelog.hpp, gs_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