Add 'maxTime' argument

[ChrisJefferson]

Add 'maxTime' argument.

Fixes #50 , and based on a patch in that issue, updated for current git head

[codecov]

Codecov Report

Merging #51 (bbc55ab) into master (4c76756) will decrease coverage by 1.0%.
The diff coverage is 84.6%.

❗ Current head bbc55ab differs from pull request most recent head 1974803. Consider uploading reports for the commit 1974803 to get more accurate results

Additional details and impacted files

@@           Coverage Diff            @@
##           master     #51     +/-   ##
========================================
- Coverage    95.1%   94.1%   -1.0%     
========================================
  Files           3       3             
  Lines         144     154     +10     
  Branches       14      15      +1     
========================================
+ Hits          137     145      +8     
- Misses          3       4      +1     
- Partials        4       5      +1     

Files	Coverage Δ
gap/curl.gd	100.0% <ø> (ø)
gap/curl.gi	100.0% <100.0%> (ø)
src/curl.c	91.1% <50.0%> (-1.8%)	⬇️

[ChrisJefferson]

Just rebased this, added another test (realised there was only tests that check for failure, none that check for success!) I did also check the timeout works and stops, but it's hard to test that because on fast internet, it's hard to set a small enough timeout it definately times out.