add --enable-webkit configure option
include gtkhtml header
update version
fix gtkhtml detection
change webkithtml default option to no
add gtkhtml limited support
remove ui.[ch]
add UI related codes from ui.[ch]
show WebKitGTK detection on console
show GtkHTML detection message
follow changed filename
add SYLPF_ prefix
include missing header for dgettext
add prototype declaration
remove SYLPF_FUNC macros
add missing header for g_strconcat
follow changed filename
report configuration result
add Clang check
add --enable-debug