Umoria 5.7.11

• Rename several ui_inventory.cpp functions to avoid name clashes (bugfix).
• Player ToHit/Armor/Damage Adjustment functions now return int16 types.
• Minor style changes.
• Various CMakeLists.txt updates:
  • Allow out-of-source builds.
  • Use configure_file to set variables in splash.txt and versions.txt.
  • Remove unneeded make install.
  • Fix for finding ncurses on Linux/macOS.
  • GCC 8 support.
• Update AUTHORS: add more known features from -JWT-.