* strop.c (scm_string_capitalize_x, scm_string_capitalize): new

	* strop.c (scm_string_capitalize_x, scm_string_capitalize): new
	functions; capitalize the first letter of each word in the
	argument string, and downcase the rest.
	(scm_string_ci_to_symbol): string->symbol, such that the same
	symbol is returned for any argument where the only difference
	between strings is in capitalization.
	(scm_string_upcase, scm_string_downcase): non-destructive
	versions.
	* strop.c (scm_substring_move_left_x, scm_substring_move_right_x):
	changed to use memmove.
	* strop.c (scm_i_index): removed the pos arguments (it's only
	called twice, and each time it's SCM_ARG1, SCM_ARG2, SCM_ARG3,
	SCM_ARG4).
	* strop.h: fixed prototypes.
*	* strop.c (scm_substring_move_left_x, scm_substring_move_right_x):
	changed to have 5 required args, rather than 2 required, and 3 required
	rest args. Also modified to allow str1 & str2 to overlap.
	(scm_substring_fill_x): changed to 4 args, rather than 2 args and
	2 required rest args.