Added support for more duration types.

[dpi]

Added support for alternative intervals for edit command.

For example you can use:

Fraction of hour (Redmine style):

• 15 minutes: tl edit FOO .25
• 1hour 15 minutes: tl edit FOO 1.25

Minutes:

• 30 minutes: tl edit FOO :30
• 1 hour 30 minutes: tl edit FOO 1:30

Friendly intervals:

• 1 hour 30 minutes: tl edit FOO 1h30m
• 1 hour 30 minutes: tl edit FOO '1h 30m'
• 15 minutes: tl edit FOO 900s
• 1 day: tl edit FOO 1d

Also fixed edit command accepting invalid slot IDs without error.

[larowlan]

Could you merge master on this one @dpi

[larowlan]

nice work mate, love the use of a utility

[dpi]

@larowlan, pushed some changes