[Proposal] Add contentDisposition to Response::download

So we can inline files (like images etc), instead of `Response::download($file)->setContentDisposition('inline')`
Add getMorphType() and getMorphClass() to MorphToMany
Default parameters to empty array.
Check whether a view lacks a bound variable

This is useful when I want to make a form add an option based on the level of the user. This test allows me to check that that information is missing when the current user does not have the required level.
Merge pull request #3915 from lazychaser/4.1

Add getMorphType() and getMorphClass() to MorphToMany
More minor cs fixes
make test fail if a view is not returned
Merge pull request #3919 from GrahamCampbell/4.1-fixes

More Minor CS Fixes
Merge pull request #3917 from ravloony/4.1

[Proposal] Add an assertion that checks whether a view lacks a given variable. (Was against master branch)
Working on comments. Updating change log.
Merge pull request #3910 from barryvdh/patch-1

[Proposal] Add contentDisposition to Response::download
Shorten variable name.
Add --heads option to sub-tree split.
[Bug] DatabasePresenceVerifier not working for booleans in the additional conditions #3927 

Change comparison operator from 'Equal' to 'Identical' when comparing value to 'NULL'/'NOT_NULL', so a comparison with a boolean value returns correct result.
Fixed swiftmailer dependency
Merge pull request #3939 from GrahamCampbell/4.1-swiftmailer

[4.1] Fixed Swiftmailer Dependency
Added whereDay() whereMonth() and whereYear()
To all the database systems I give a vague shite about
MONTH() YEAR() DAY() seem common enough
If 3 of the 4 are the same then it makes sense to just shove them in Grammar.php, and let SQLite be the exception. Still testing the 4 separately though, as that seems rather important.
Merge branch '4.1' of https://github.com/laravel/framework into feature/whereDayMonthYear
Merge pull request #3928 from lpopov/4.1

[Bug] DatabasePresenceVerifier not working for booleans in the additional conditions #3927