updated for version 7.4.280
Problem:    When using a session file the relative position of the cursor is
	    not restored if there is another tab. (Nobuhiro Takasaki)
Solution:   Update w_wrow before calculating the fraction.
Added tag v7-4-280 for changeset daf7e98675cf
updated for version 7.4.281
Problem:    When a session file has more than one tabpage and 'showtabline' is
	    one the positions may be slightly off.
Solution:   Set 'showtabline' to two while positioning windows.
Added tag v7-4-281 for changeset 24c90f1fec85
updated for version 7.4.282
Problem:    Test 97 fails on Mac.
Solution:   Do not ignore case in file names. (Jun Takimoto)
Added tag v7-4-282 for changeset 6d0a1132dd71