Make lexing ARM-friendly

[duck2]

The current trie lexer makes use of the fast unaligned 32/64 bit access found in amd64 architectures:

inline enum_pin_type lex_pin_type(const char *in){
	unsigned int len = strlen(in);
	switch(len){
	case 4:
		switch(*((triehash_uu32*)&in[0])){
		case onechar('O', 0, 32) | onechar('P', 8, 32) | onechar('E', 16, 32) | onechar('N', 24, 32):
			return enum_pin_type::OPEN;
[...]
}

This might run slower in other architectures. Add a knob to uxsdcxx to generate "flat" tries.