Tcod

Fixed
- Fixed possible crash in `TCOD_mouse_move`.

Added
- Added the `TCOD_clear_error` and `TCOD_set_errorf` functions.
- Added an error code enum: `TCOD_Error`.

Changed
- Console blit operations now perform per-cell alpha transparency.
- When a renderer fails to load it will now fallback to a different one.
The order is: OPENGL2 -> OPENGL -> SDL2.

Deprecated
- The use of `libtcod.cfg` or `terminal.png` is deprecated.

Fixed
- The following are no longer mislabeled as taking const images:
- `TCOD_image_get_mipmap_pixel`
- `TCOD_image_blit`
- `TCOD_image_blit_rect`
- `TCOD_sys_update_char` now works with the newer renderers.
- Fixed buffer overflow in name generator.
- `TCOD_image_from_console` now works with the newer renderers.
- New renderers now auto-load fonts from `libtcod.cfg` or `terminal.png`.

Changed
- Renamed build systems directory from `build/` to `buildsys/`.

Fixed
- `OPENGL` and `GLSL` renderers were not properly clearing space characters.

Changed
- `TCOD_image_blit_2x` now renders using Unicode block elements instead of a
custom encoding.

Fixed
- Libtcod will no longer segfault if it's statically linked to an executable.

Added
- `TCODConsole::get_data` method for getting the C struct pointer from C++.

Fixed
- `TCOD_map_compute_fov` will now silently ignore out-of-bounds coordinates
instead of crashing.
- Changing the tiles of an active tileset will now work correctly.

Added
- You can now set the `TCOD_RENDERER` and `TCOD_VSYNC` environment variables to
force specific options to be used.
Example: ``TCOD_RENDERER=sdl2 TCOD_VSYNC=1``

Changed
- `TCOD_sys_set_renderer` now returns an error status.
- `TCODSystem::setRenderer` will now throw instead of terminating on an error.
- `TCOD_console_init_root` and `TCOD_sys_set_renderer` are now no-discard.

Fixed
- `TCOD_console_map_ascii_code_to_font` functions will now work when called
before `TCOD_console_init_root`.