Update testing case

- Testing case for set and get doc properties
- Update charts struct XML tags

Add the ability to change the default font

Closes #390

typo fixed

* Rewrite prepareSheetXML to scale linearly

We don't need to backfill columns into every row for most purposes
Provided makeContiguousColumns for setting styles where we do
need it for a specific region.

Added a benchmark to monitor progress. For 50,000 rows this went
from about 11 seconds to 1 second. The improvements are more
dramatic as the row/column count increases.

* Assigning that row value was redundant

add error return value

exported functions:

GetMergeCells
ProtectSheet
UnprotectSheet
UpdateLinkedValue
GetMergeCells
SetSheetVisible

inner functions:

workSheetReader
copySheet

Fix two bugs related to Formula

fix calc object position  for addPicture

Fix file corruption issue when deleting a sheet containing a formula.

The target cell for calclator the height was shifted by 1.

The target cell for calclator the width was shifted by 1.

Do not save duplicate images

Adding the same image should create a drawing referencing the
already stored copy of the image.

Closes #359

Exported functions:

SetCellStyle
InsertCol
RemoveCol
RemoveRow
InsertRow
DuplicateRow
DuplicateRowTo
SetRowHeight
GetRowHeight
GetCellValue
GetCellFormula
GetCellHyperLink
SetCellHyperLink
SetCellInt
SetCellBool
SetCellFloat
SetCellStr
SetCellDefault
GetCellStyle
SetCellValue
MergeCell
SetSheetRow
SetRowVisible
GetRowVisible
SetRowOutlineLevel
GetRowOutlineLevel
GetRows
Columns
SearchSheet
AddTable
GetPicture
AutoFilter
GetColVisible
SetColVisible
GetColOutlineLevel
SetColOutlineLevel
SetColWidth
GetColWidth

inner functions:

adjustHelper
adjustMergeCells
adjustAutoFilter
prepareCell
setDefaultTimeStyle
timeToExcelTime
addDrawingChart
addDrawingVML
addDrawingPicture
getTotalRowsCols
checkRow
addDrawingShape
addTable

* Add benchmark for adding images to sheet

This should help track performance regressions in future changes.

* Only transform sheet name if necessary

This allows the user to set a floating point value into a
cell with a specific number of places after the decimal.

Closes #357