Fixed a crash in the LLL parser (when you input non-ascii characters); minor GUI tweak.

The crash happens sometimes when you input any sort of non-ascii characters, e.g. the Italian accented letter ò (typing a non-ascii character alone seems the easiest way to reproduce).
Using boost::spirit::standard instead of boost::spirit::ascii seems to prevent the crash.

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Improved the GUI a little, to prevent the text widgets from scrolling down all the way when visualizing blocks, pending transactions or contract info.