MP1: Automatic cresc/dim should not be added if pause is too short

[rualark]

This is needed because:

• Nonlegato transition has a pause shorter than 100/1024 ticks
• Short pauses usually do not require cresc/dim

[rualark]

Solution:

• If this is a first note, allow cresc/dim
• If this note is preceded by pause
• If this note is not preceded by pause, prohibit cresc/dim
• If pause before ntote is shorter than 100ms, prohibit cresc/dm
• If pause before ntote is a nonlegato pause (shorter than 100/1024 ticks), prohibit cresc/dm