lib/unicodesymbols tests and fixes.

lib/unicodesymbols tests and fixes.

Test unicodesymbols for most supported input encodings with Kornel's addition to ctests.

Add required "forces" to unicodesymbols:
* utf8x does not support all characters supported by LyX
* several 8-bit encodings map characters to math-mode commands - force replacement in text-mode so that LyX can wrap them in \\ensuremath.

Fix a misalignment (wrong replacements) in the Cyrillic Unicode block.

Use \\mathscr for Mathematical Script characters in Mathematical Alphanumeric Characters (in line with the characters in other unicode blocks.