build.sh: added extra checks and some informational messages, also now all the files from src/ are being copied and the .js is compressed in-place.
Added _2d_between() helper to check if a coordinate is in the bounding box of two others.
Renamed gfx_render_fire_particle() as it is a gfx helper.
Renamed texture_show() to gfx__texture_put(), texture_create() to gfx__texture_create() as they are a gfx helpers.
Fixed a call for gfx_render_fire_particle() instead of gfx__render_fire_particle().
Renamed gui_render_button() to gfx__render_gui_button() as it is a gfx helper.
Renamed gui_render_bar_background() to gfx__render_gui_bar_background() as it is a gfx helper.
Renamed gui_render_bar() to gfx__render_gui_bar() as it is a gfx helper.
Replaced layer-by-layer render approach to a tile-by-tile one. Works really nicely, still approximate and needs more work.