Change types in XML_ParserStruct

[rinon]

We'll start by planning out changes here, then incrementally make those changes through the codebase.

Raw pointer fields that need replacing:

• [ ] pub m_userData: *mut c_void
• [ ] pub m_handlerArg: *mut c_void
• [ ] pub m_buffer: *mut c_char
• [ ] pub m_mem: crate::expat_h::XML_Memory_Handling_Suite
• [ ] pub m_bufferPtr: *const c_char
• [ ] pub m_bufferEnd: *mut c_char
• [ ] pub m_bufferLim: *const c_char
• [ ] pub m_parseEndPtr: *const c_char
• [ ] pub m_dataBuf: *mut crate::expat_external_h::XML_Char
• [ ] pub m_dataBufEnd: *mut crate::expat_external_h::XML_Char
• [x] pub m_startElementHandler: crate::expat_h::XML_StartElementHandler
• [x] pub m_endElementHandler: crate::expat_h::XML_EndElementHandler
• [x] pub m_characterDataHandler: crate::expat_h::XML_CharacterDataHandler
• [x] pub m_processingInstructionHandler: crate::expat_h::XML_ProcessingInstructionHandler
• [x] pub m_commentHandler: crate::expat_h::XML_CommentHandler
• [x] pub m_startCdataSectionHandler: crate::expat_h::XML_StartCdataSectionHandler
• [x] pub m_endCdataSectionHandler: crate::expat_h::XML_EndCdataSectionHandler
• [x] pub m_defaultHandler: crate::expat_h::XML_DefaultHandler
• [x] pub m_startDoctypeDeclHandler: crate::expat_h::XML_StartDoctypeDeclHandler
• [x] pub m_endDoctypeDeclHandler: crate::expat_h::XML_EndDoctypeDeclHandler
• [x] pub m_unparsedEntityDeclHandler: crate::expat_h::XML_UnparsedEntityDeclHandler
• [x] pub m_notationDeclHandler: crate::expat_h::XML_NotationDeclHandler
• [x] pub m_startNamespaceDeclHandler: crate::expat_h::XML_StartNamespaceDeclHandler
• [x] pub m_endNamespaceDeclHandler: crate::expat_h::XML_EndNamespaceDeclHandler
• [x] pub m_notStandaloneHandler: crate::expat_h::XML_NotStandaloneHandler
• [x] pub m_externalEntityRefHandler: crate::expat_h::XML_ExternalEntityRefHandler
• [x] pub m_externalEntityRefHandlerArg: crate::expat_h::XML_Parser
• [x] pub m_skippedEntityHandler: crate::expat_h::XML_SkippedEntityHandler
• [x] pub m_unknownEncodingHandler: crate::expat_h::XML_UnknownEncodingHandler
• [x] pub m_elementDeclHandler: crate::expat_h::XML_ElementDeclHandler
• [x] pub m_attlistDeclHandler: crate::expat_h::XML_AttlistDeclHandler
• [x] pub m_entityDeclHandler: crate::expat_h::XML_EntityDeclHandler
• [x] pub m_xmlDeclHandler: crate::expat_h::XML_XmlDeclHandler
• [ ] pub m_encoding: *const crate::src::lib::xmltok::ENCODING
• [x] pub m_initEncoding: crate::src::lib::xmltok::INIT_ENCODING
• [x] pub m_internalEncoding: *const crate::src::lib::xmltok::ENCODING
• [ ] pub m_protocolEncodingName: *const crate::expat_external_h::XML_Char
• [x] pub m_unknownEncodingMem: *mut c_void
• [ ] pub m_unknownEncodingData: *mut c_void
• [ ] pub m_unknownEncodingHandlerData: *mut c_void
• [ ] pub m_unknownEncodingRelease: Option<unsafe extern "C" fn(_: *mut c_void) -> ()>
• [ ] pub m_processor: Option<Processor>
• [ ] pub m_eventPtr: *const c_char
• [ ] pub m_eventEndPtr: *const c_char
• [ ] pub m_positionPtr: *const c_char
• [ ] pub m_openInternalEntities: *mut OPEN_INTERNAL_ENTITY
• [ ] pub m_freeInternalEntities: *mut OPEN_INTERNAL_ENTITY
• [ ] pub m_declEntity: *mut ENTITY
• [ ] pub m_doctypeName: *const crate::expat_external_h::XML_Char
• [ ] pub m_doctypeSysid: *const crate::expat_external_h::XML_Char
• [ ] pub m_doctypePubid: *const crate::expat_external_h::XML_Char
• [ ] pub m_declAttributeType: *const crate::expat_external_h::XML_Char
• [ ] pub m_declNotationName: *const crate::expat_external_h::XML_Char
• [ ] pub m_declNotationPublicId: *const crate::expat_external_h::XML_Char
• [ ] pub m_declElementType: *mut ELEMENT_TYPE
• [ ] pub m_declAttributeId: *mut ATTRIBUTE_ID
• [ ] pub m_dtd: *mut DTD
• [ ] pub m_curBase: *const crate::expat_external_h::XML_Char
• [ ] pub m_tagStack: *mut TAG
• [ ] pub m_freeTagList: *mut TAG
• [ ] pub m_inheritedBindings: *mut BINDING
• [ ] pub m_freeBindingList: *mut BINDING
• [ ] pub m_atts: *mut crate::src::lib::xmltok::ATTRIBUTE
• [ ] pub m_nsAtts: *mut NS_ATT
• [ ] pub m_tempPool: STRING_POOL
• [ ] pub m_temp2Pool: STRING_POOL
• [ ] pub m_groupConnector: *mut c_char
• [ ] pub m_parentParser: crate::expat_h::XML_Parser

[rinon]

Handler fields were replaced in #9.

[rinon]

m_initEncoding, m_unknownEncodingMem, and m_internalEncoding were made safe in #19.