OpenSystemsDevelopment / qpdf

Also, modernize for loop.

Instead of overwriting cur_row.data() use clear and insert.

Tighten checks for invalid indirect references  during xref reconstru…

Handle default-constructed JSON objects

Tighten checks for invalid indirect references in QPDFParser

Update .clang-format to require braces after control statements

Fix incorrect handling of invalid negative object ids

Fix two errors introduced in #1110 and #1112. Since
#1110, encountering the invalid indirect reference #1110
-2147483648 n R produces an integer underflow which, if
 undetected, immediately trigger a logic error. Since
 #1112, object -1 0 R may be incorrectly identified as
 an earlier generation of itself and deleted,
 invalidating a live iterator.

Use std::vector instead of list and move shared pointers

This is just QPDFJob wiring.

...since they have to be handled before other options. It was working
because, in both cases, `file` was alphabetically before the other
keys, but this implementation gives a stronger guarantee.