Remove <filesystem>

Should fix compilation with GCC before 9

include/gfx/main.hpp

@@ -10,9 +10,9 @@
 #define RGBDS_GFX_MAIN_HPP
 
 #include <array>
-#include <filesystem>
 #include <limits.h>
 #include <stdint.h>
+#include <string>
 #include <vector>
 
 #include "helpers.h"
@@ -27,7 +27,7 @@ struct Options {
 	bool beVerbose = false; // -v
 	bool columnMajor = false; // -Z, previously -h
 
-	std::filesystem::path attrmap{}; // -a, -A
+	std::string attrmap{}; // -a, -A
 	std::array<uint8_t, 2> baseTileIDs{0, 0}; // -b
 	enum {
 		NO_SPEC,
@@ -39,14 +39,14 @@ struct Options {
 	std::array<uint32_t, 4> inputSlice{0, 0, 0, 0}; // -L
 	std::array<uint16_t, 2> maxNbTiles{UINT16_MAX, 0}; // -N
 	uint8_t nbPalettes = 8; // -n
-	std::filesystem::path output{}; // -o
-	std::filesystem::path palettes{}; // -p, -P
+	std::string output{}; // -o
+	std::string palettes{}; // -p, -P
 	uint8_t nbColorsPerPal = 0; // -s; 0 means "auto" = 1 << bitDepth;
-	std::filesystem::path tilemap{}; // -t, -T
+	std::string tilemap{}; // -t, -T
 	std::array<uint16_t, 2> unitSize{1, 1}; // -U (in tiles)
 	uint64_t trim = 0; // -x
 
-	std::filesystem::path input{}; // positional arg
+	std::string input{}; // positional arg
 
 	format_(printf, 2, 3) void verbosePrint(char const *fmt, ...) const;
 	uint8_t maxPalSize() const {