patch 8.0.0542: getpos() can return a negative line number

Problem:    getpos() can return a negative line number. (haya14busa)
Solution:   Handle a zero topline and botline. (closes vim#1613)

patch 8.0.0541: compiler warning on MS-Windows

Problem:    Compiler warning on MS-Windows.
Solution:   Add a type cast. (Mike Williams)

patch 8.0.0540: building unit tests fails

Problem:    Building unit tests fails.
Solution:   Move params outside of #ifdef.

patch 8.0.0539: startup test fails on Mac

Problem:    Startup test fails on Mac.
Solution:   Use another term name, "unknown" is known. Avoid a 2 second delay.

patch 8.0.0538: no test for falling back to default term value

Problem:    No test for falling back to default term value.
Solution:   Add a test.

patch 8.0.0537: illegal memory access with :z and large count

Problem:    Illegal memory access with :z and large count.
Solution:   Check for number overflow, using long instead of int. (Dominique
            Pelle, closes vim#1612)

patch 8.0.0536: quickfix window not updated when freeing quickfix stack

Problem:    Quickfix window not updated when freeing quickfix stack.
Solution:   Update the quickfix window. (Yegappan Lakshmanan)

patch 8.0.0535: memory leak when exiting from within a user function

Problem:    Memory leak when exiting from within a user function.
Solution:   Clear the function call stack on exit.

patch 8.0.0534: defaults.vim does not work well with tiny features

Problem:    Defaults.vim does not work well with tiny features. (crd477)
Solution:   When the +eval feature is not available always reset 'compatible'.

patch 8.0.0533: abbreviation doesn't work after backspacing newline

Problem:    Abbreviation doesn't work after backspacing newline. (Hkonrk)
Solution:   Set the insert start column. (closes vim#1609)