missing #includes complaints by MSVC 2017

[Pavel Sanda]

On Sat, Oct 24, 2020 at 11:10:47AM +0300, Yuriy Skalko wrote:
> >Dear LyX developers,
> >
> >I just tried to compile LyX (commit
> >2c1753a5265c59ebd11fc465cdb119ff589ad965) on windows 10 with MSVC 2017
> >toolkit, and encountered compiling errors of the sort:
> >
> >
> >   src\DocIterator.h(335): error C2039: 'min': is not a member of 'std
> 
> Pavel, please check da8b5de97. Should <algorithm> be moved back from .cpp
> files?
> 
> In GCC `min` is defined via including <vector>.

Yes, committed, thanks.

> >and another one about std::isspace.
> 
> As I understand, lyx::isSpace should be used instead in these 2 places. I've
> corrected this in attached patch.

Please go on.

Pavel