patch 8.0.0160: EMSG() is sometimes used where it should be IEMSG()

Problem:    EMSG() is sometimes used for internal errors.
Solution:   Change them to IEMSG(). (Dominique Pelle)  And a few more.

patch 8.0.0159: crash on startup when updating tabline

Problem:    Using a NULL pointer when using feedkeys() to trigger drawing a
            tabline.
Solution:   Skip drawing a tabline if TabPageIdxs is NULL. (Dominique Pelle)
            Also fix recursing into getcmdline() from the cmd window.

patch 8.0.0158: float funcion test fails on MS-Windows

Problem:    On MS-Windows some float functions return a different value when
            passed unusual values.  strtod() doesn't work for "inf" and "nan".
Solution:   Accept both results.  Fix str2float() for MS-Windows.  Also
            reorder assert function arguments.

patch 8.0.0157: no completion for :syntax spell and :syntax sync

Problem:    No command line completion for ":syntax spell" and ":syntax sync".
Solution:   Implement the completion. (Dominique Pelle)

patch 8.0.0156: not enough test coverage for float functions

Problem:    Several float functions are not covered by tests.
Solution:   Add float tests. (Dominique Pelle)

patch 8.0.0155: ubsan complains about NULL pointer

Problem:    When sorting zero elements a NULL pointer is passed to qsort(),
            which ubsan warns for.
Solution:   Don't call qsort() if there are no elements. (Dominique Pelle)

patch 8.0.0154: system() test fails on OS/X

Problem:    system() test fails on OS/X.
Solution:   Deal with leading spaces.

patch 8.0.0153: system() test fails on MS-Windows

Problem:    system() test fails on MS-Windows.
Solution:   Deal when extra space and CR.

patch 8.0.0152: stray channellog created when running tests

Problem:    Running the channel test creates channellog.
Solution:   Delete the debug line.

patch 8.0.0151: passing buffer content to system() is clumsy

Problem:    To pass buffer content to system() and systemlist() one has to
            first create a string or list.
Solution:   Allow passing a buffer number. (LemonBoy, closes vim#1240)