Arbitraries for constants and record creation

Main features:

• more arbitraries: constantFrom and record

Commit log:
0ed31cc Add with_deleted_keys setting to settings example
18f7546 Add settings combination example
9de313b Fix knight example
344cc89 Typos in test name
6be205e Bump versions in packages.json
6167172 Add e2e test for record
4db0087 Update README.md
d447668 Revamp knight example using fc.record
fc9d0d7 Revamp e2e test Shadows.spec using fc.record
786e16e Redefine default values of ObjectArbitrary
a055e7f Documentation record
a3ed2b6 Documentation constantFrom
036cd2f Documentation noShrink
0ee3a03 Link towards jsDelivr
8984e78 Add with_deleted_keys option for record
cc2276b Add e2e test for record
850158b Add an arbitrary able to generate records
547b070 Add Stream.getNthOrLast
9fca382 Fix wrongly designed constantFrom test
f817c30 Fix typo
262b809 Add the ability to select one of the constants using fc.constantFrom
6db53f2 Exclude example/ from npm package
830669c Fix travis CI build
dac81ae Add e2e tests to check utf16 validity
30f4d6a Try to fix travis build