Fix block notation to be more idiomatic

Ruby idioms dictate that blocks using curly braces should not be
multiline. These blocks were not complex enough to warrant being
multiline, so let's make them one-liners instead.

Signed-off-by: David Celis <me@davidcel.is>
Fix a typo (milimeters)

Signed-off-by: David Celis <me@davidcel.is>
Multiline blocks should use do-end

Signed-off-by: David Celis <me@davidcel.is>
Fix dubious whitespace issues

Signed-off-by: David Celis <me@davidcel.is>