More notation symbols for v1.2

[hajicj]

The following symbols need to be added to the symbol list, and their respective grammar rules to the grammar file. Keep it backward-compatible by adding them at the end!

• [x] figured_bass_text (supersymbol for numerals, sharps, flats, etc.)
• [x] system_separator (those two slashes in default grayscale image)
• [x] continuation/connection_dash (occurs in texts, should depend on text but not directly a part of it
• [x] transposition_text (for 8va, 8 at clefs, 15va, etc.)
• [x] dotted_barline
• [x] horizontal_spanner (the top-side bracket in voltas, transpositions, etc.)
• [x] dotted_horizontal_spanner (the top-side bracket in voltas, transpositions, etc.)
• [x] breath_mark

These two are still up for discussion:

• [x] staffline (this is a somewhat contentious symbol)
• [x] staff (combines stafflines)

[hajicj]

Add dependency rules:

• [x] transposition_text to 8, v, a
• [x] clef to transposition_text
• [x] figured_bass to numerals, unclassified, accidentals
• [x] any text to continuation/connection_dash
• [x] volta to horizontal_spanner
• [x] transposition_text to horizontal_spanner

[hajicj]

Document the new symbols in instructions!

[hajicj]

Page number is already served by other_numeric_sign.

[hajicj]

Done.