Add SetSheetViewOptions()

Two new methods:
- SetSheetViewOptions(sheetName string, viewIndex int, opts ...SheetViewOption) error
- GetSheetViewOptions(sheetName string, viewIndex int, opts ...SheetViewOptionPtr) error

The option values are given by the user through types that have privates methods
that implement the private SheetViewOption and SheetViewOptionPtr interfaces:
- DefaultGridColor(bool)
- RightToLeft(bool)
- ShowFormulas(bool)
- ShowGridLines(bool)
- ShowRowColHeaders(bool)

Examples:
    err := xl.SetSheetViewOptions("Sheet1", -1, excelize.ShowGridLines(true))

    var showGridLines excelize.ShowGridLines
    err := xl.GetSheetViewOptions("Sheet1", -1, &showGridLines)

Fixes #145.

Add missing XML attributes `customWorkbookViews` and `customWorkbookView` in the workbook, relate issue #152.
Signed-off-by: Ri Xu <xuri.me@gmail.com>

Signed-off-by: Ri Xu <xuri.me@gmail.com>

fix OpenReader no sheet error

- godoc updated

Signed-off-by: Ri Xu <xuri.me@gmail.com>

Signed-off-by: Ri Xu <xuri.me@gmail.com>

- go test and godoc updated
Signed-off-by: Ri Xu <xuri.me@gmail.com>

travis: update go versions

- API changed, use worksheet name instead of "sheet" + index, related issue #25, #43, #47, #51, #89, #101, #116 and #120.
- go test updated

change the TitleToNumber function

Test

- go test and readme update

Conut and trim sheet name in UTF-8

- go test and godoc updated

- go test added

Fix round-off error in representation of date and time values

Add extra argument "Linktype" to SetCellHyperLink