reformat and better bmp all in one function

src/bmp.h

@@ -1,9 +1,3 @@
-#include <stdlib.h>
-
-#define HEADER_SIZE 54
-
-char *bmp_header(unsigned long width, unsigned long height, unsigned long color_depth);
-unsigned long bmp_data_line_length(unsigned long width, unsigned long color_depth);
-char *bmp_data_line(unsigned long width, unsigned long color_depth, char *data, unsigned long data_offset);
-unsigned long bmp_data_length(unsigned long width, unsigned long height, unsigned long color_depth);
-char *bmp_data(unsigned long width, unsigned long height, unsigned long color_depth, char *data);
+void bmp_generate(unsigned long width, unsigned long height,
+                  unsigned int color_depth, char *file_path,
+                  void generate_line(unsigned long y, char *data_buffer));