Refactor Picklists and Option Parsers

This PR refactors how picklists and option parsers are implemented in LibTidy,
making is vastly easier to implement new picklists in the future, as well as
modify some of the existing picklists such that they have more logical names.

Picklist arrays are now arrays of structures that include the possible strings
capable of setting a particular option value, and a new parser has been written
to work with these structures.

In addition, several of the existing parsers were removed, as they are now
redundant, and a couple of the remaining parsers were refactored to take
advantage of the new parser.

In effect, this means that:

- New parsers don't have to be written in the majority of cases where new
  options are added that exceed yes/no/auto.
- Some of the existing options can have more meaningful names than yes/no/auto,
  in a backward compatible way. For example, vertical-spacing "auto" currently
  in no way reflects "auto" when used.

Author: balthisar

include/tidyenum.h

@@ -724,6 +724,36 @@ typedef enum
     TidyCR          /**< Use Macintosh style: CR */
 } TidyLineEnding;
 
+    
+/** TidyEncodingOptions option values specify the input and/or output encoding.
+ ** @remark This enum's starting value is guaranteed to remain stable.
+ */
+typedef enum
+{
+    TidyEncRaw = 0,
+    TidyEncAscii,
+    TidyEncLatin0,
+    TidyEncLatin1,
+    TidyEncUtf8,
+#ifndef NO_NATIVE_ISO2022_SUPPORT
+    TidyEncIso2022,
+#endif
+    TidyEncMac,
+    TidyEncWin1252,
+    TidyEncIbm858,
+
+#if SUPPORT_UTF16_ENCODINGS
+    TidyEncUtf16le,
+    TidyEncUtf16be,
+    TidyEncUtf16,
+#endif
+
+#if SUPPORT_ASIAN_ENCODINGS
+    TidyEncBig5,
+    TidyEncShiftjis
+#endif
+} TidyEncodingOptions;
+
 
 /** Mode controlling treatment of doctype
  ** @remark This enum's starting value is guaranteed to remain stable.