Add some checking rules in lyric checker.

[andy840119]

What's should be checked in the lyric?

• at least one singer -> not really sure.
• should have a layout index.
• should have notes in beatmap.
• should have lyric text.
• should have time-tags(not really sure is checked or not.), and time-tags should wrap all the lyric, and lyric should have an end time-tag in the last of lyric.
• should have language.

[andy840119]

maybe should separate into:

• CheckLyricRubyRomaji -> CheckInvalidRubyRomajiLyrics
  • Ruby
  • Romaji
• CheckLyricProperty -> CheckInvalidPropertyLyrics
  • Singer
  • Layout
  • lyric text
  • language
• CheckLyricTimeTag -> CheckInvalidTimeLyrics
  • Time
  • Time tags
• CheckLyricRelativeNotes -> CheckInvalidRelativeNoteInLyrics
  • Generate notes if this beatmap is saitenable -> also should check is there any way not to generate notes?
  • Not missing generated notes? -> generated note might need to follow time-tags?

[andy840119]

Update :
CheckLyricTimeTag -> need more check about time-tag.
CheckLyricRelativeNotes -> waiting for implementation.