Expose scaled mazes to special level lua

Adds a new level init type which directly creates a maze,
optionally setting corridor width and wall thickness,
and removing dead ends.

des.level_init({ style = "maze", corrwid = 3, wallthick = 1, deadends = false });

include/sp_lev.h

@@ -38,6 +38,7 @@ enum lvlinit_types {
     LVLINIT_NONE = 0,
     LVLINIT_SOLIDFILL,
     LVLINIT_MAZEGRID,
+    LVLINIT_MAZE,
     LVLINIT_MINES,
     LVLINIT_ROGUE,
     LVLINIT_SWAMP
@@ -110,6 +111,8 @@ typedef struct {
     boolean smoothed, joined;
     xchar lit, walled;
     boolean icedpools;
+    int corrwid, wallthick;
+    boolean rm_deadends;
 } lev_init;
 
 typedef struct {