V1.3 Sources and metadata adjustments

[FredShallcrass]

Changes to sources

• Updated artwork for spacing grave (backtick) in sources
• Updated artwork dash alignment. Closes #5
• Improved language support through ccmp and mark features in sources. Closes #10
• Improved linking of styles in sources. Closes #41

This includes manual updates included in pull Request #27.

• Updated font naming in sources
• Updated licensing info as per Google fonts request in sources

Note: Hinting sources + otf, ttf, woff and woff2 font releases to follow.

[moyogo]

This reintroduces the glyph classes @deadMarks and @deadbelowMarks and the lookups DblMarks and CmbMarks using them to substitute spacing marks by non-spacing marks.

All spacing marks, no just /grave U+0060, must behave like spacing marks and remain spacing whether they follow a letter or not. Spacing marks characters should be used for spacing marks, non-spacing marks characters should be used for non-spacing marks. There should not be any substitution from spacing to non-spacing.

These two lookups and these glyph classes should be removed.