#5639 compile with -std=c++11

[Dan Eble]

In addition to enabling C++11, I updated various things that I either
remembered or found by searching for "C++11." Each of these is a
separate commit to make it easy to revert in case that is necessary.

1: compile with -std=c++11
2: comments
3: Use C++11 for Input construction & assignment
4: auto_ptr -> unique_ptr
5: explicit bool conversion for Dimension_cache::Optional
6: shrink_to_fit () after filtering a Grob_array
7: use =delete for non-copiable classes

https://codereview.appspot.com/553310045

[Anonymous]

Passes make, make check and a full make doc.

[Anonymous]

Patch on countdpwn for Dec 19th

[Anonymous]

Patch counted down - please push

[Dan Eble]

commit 8b6f5c50d9a5d890c9f2338efa055588f5fd9b89 (HEAD -> staging, origin/staging)
Author: Dan Eble <nine.fierce.ballads@gmail.com>
Date:   Fri Dec 13 22:59:54 2019 -0500

    Issue 5639/7: use =delete for non-copiable classes

commit 356dde44d54f3e289dc928dd1cd0260f164135d2
Author: Dan Eble <nine.fierce.ballads@gmail.com>
Date:   Fri Dec 13 11:28:49 2019 -0500

    Issue 5639/6: shrink_to_fit () after filtering a Grob_array

commit bb98889b12c7376bda6022e654190ca2325aa43d
Author: Dan Eble <nine.fierce.ballads@gmail.com>
Date:   Fri Dec 13 11:19:01 2019 -0500

    Issue 5639/5: explicit bool conversion for Dimension_cache::Optional

commit 1ae63269de784f7d55c2613c2c9a4b38571c52fb
Author: Dan Eble <nine.fierce.ballads@gmail.com>
Date:   Fri Dec 13 11:03:10 2019 -0500

    Issue 5639/4: auto_ptr -> unique_ptr

commit 68e4f4cbaac9ab543cd40be39797c1fa4c775e9f
Author: Dan Eble <nine.fierce.ballads@gmail.com>
Date:   Fri Dec 13 11:00:38 2019 -0500

    Issue 5639/3: Use C++11 for Input construction & assignment

commit 3a790fd3d31354538bb411bf6ff20c008ca08f98
Author: Dan Eble <nine.fierce.ballads@gmail.com>
Date:   Fri Dec 13 10:43:35 2019 -0500

    Issue 5639/2: Update comment on template parameter packs

commit 885a6963b0cfcfd21d9098ca2fca42dd37500594
Author: Dan Eble <nine.fierce.ballads@gmail.com>
Date:   Tue Dec 10 12:03:12 2019 -0500

    Issue 5639/1: Compile with -std=c++11