Misc. fixes

• Improved validation of stories, to avoid creating non-functional character links in the shared stories. Character links (eg. {10} ) in stories are properly validated, and otherwise an error message will show up. Only Heisig frame numbers, and characters belonging to the CJK Unified Ideograph range can be used in those links.
• Fixed highlighting of kanji in the Reading page (thanks hanysz)

Non-Heisig characters in the Study pages
This isn't a new feature, but many users may not be aware. As of writing, there are 12559 characters in the database accessible in the Study pages. To navigate to "non-Heisig" characters, you can either type the character in the search box, or enter its unicode value, for example 19986 is 丒. At the moment, these characters get an automatic keyword like "Unicode #19986" and the keyword can not be customized. If the character has a Study page, you can create a link to it in a story by using the unicode value so eg. {19986} will link to 丒.

List of keywords changed in Dec. 3rd update
Here is a list of 5th edition keywords that have changed with the "Multiple Editions" update. As I worked on the update, I made the decision to go with the 6th edition keywords, and fall back to the 5th edition keywords for characters that are no longer in the last edition. This is a small compromise I made in order to keep the complexity of the app in check (as well as the database). I felt it was a reasonable compromise for the following reasons. First, 12 of these are in Volume 1, and the remaining 28 changed keywords are for Volume 3, which concerns a much smaller group of the user base. And secondly, users can customize these keywords if they already commited them to memory, and otherwise it is probably a good idea to go with the new edition keywords.