DuckDuckGo: Add the `use` statement at the top.
DuckDuckGo: Remove the "-" in "t-shirt".

Perl thinks that "t" is a bareword.
DuckDuckGo: Continuation of #363.

Pros:
- No more problems with *_html such as https://duckduckgo.com/?q=duckduckgo+help_html.

Cons:
- No plain text version (only affects the API so it's not that big of a deal).
- Triggers with "duckduckgo" and "ddg" only so "zeroclickinfo" on its own won't trigger.
DuckDuckGo: Update tests.
.
add nanoseconds, add scientific notation where answers non-sensical, add precision support for later re-factoring, remove duplicate tests, add more tests, add more units (digital)
Conversions: Adding nanoseconds, digital units, sci-precision support (implemented by @elohmrow)
fixing ParseCron merge conflict
.
Merge pull request #366 from quovadit/CalendarToday

CalendarToday: use correct timezone
Apply tidy.
Add code and tests for number disambiguation.

This is still not properly factored, but progressing.
Update license
Update license -> Apache2
not apache 2_0_2_0.

good job, me.
re-factored Conversions goodie to use Convert::Pluggable
GenerateMAC: Remove the "More at ..." link.
SumOfNaturalNumbers: Simplify the triggering.
SumOfNaturalNumbers: Faster computation.

- Don't use List::Util for computing the number.
- Stricter regexp.
- Add attribution.
SumOfNaturalNumbers: Add a "from" in the regexp.

So that it can accept "add from 1 to 100"