changes in convert/text functions

- changed function names: PascalCase to snake_case
- templates functions moved to a seperate file (text_private.h)
- as a public api only available functions with char/wchar_t/std::string/std::wstring
- ToLower(...) changed to to_lower_emplace(...), similar ToUpper(...) to to_upper_emplace(...)
- added functions:
  std::string to_lower(const std::string & str);
  std::string to_upper(const std::string & str);
  and with std::wstring too
- functions with postfix 'NoCase' changed to 'nc'

src/space/space.cpp

@@ -1614,7 +1614,7 @@ Space * Space::get_object_field_nc(const wchar_t * field)
 
 		while( i != value.value_object.end() )
 		{
-			if( EqualNoCase(field, i->first.c_str()) )
+			if( is_equal_nc(field, i->first.c_str()) )
 			{
 				return i->second;
 			}
@@ -1639,7 +1639,7 @@ const Space * Space::get_object_field_nc(const wchar_t * field) const
 
 		while( i != value.value_object.cend() )
 		{
-			if( EqualNoCase(field, i->first.c_str()) )
+			if( is_equal_nc(field, i->first.c_str()) )
 			{
 				return i->second;
 			}