Go 1.15 and later required, #65 fn: IMABS, IMCOS, IMCOSH, IMCOT, IMCSC, IMCSCH, IMEXP, IMLN and IMLOG10

typo fixed

This closes #785, support to change tab color; new formula function: FISHER, FISHERINV, GAMMA, GAMMALN, MIN, MINA, PERMUT

lint issue fixed and new formula function: ATAN, AVERAGE, AVERAGEA, CONCAT, CONCATENATE, COUNT, COUNTBLANK, MAX

This closes #657 and closes #748, AddChart support custom marker symbol and symbol size, fix AddPicture auto fit failure with multi merged cells

- Avoid to create duplicate style
- Update unit test for the auto filter
- Init code scanning alerts

Default row height compatibility with Apache OpenOffice and Kingsoft WPS, unit test update and typo fixed

* Resolve #661 Add Logarithmic scale option support on Y axis

Example usage:
Add the following option into the format string when using AddChart:

"y_axis":{"scaling":{"logbase":"10"}}

* Change type of LogBase from attrValString to attrVarFloat

* Add test case for testing Logarithmic Option in Y axis of charts

* Move field `LogBase` in the format string up one level (remove `Scaling`) as suggested the owner

Test cases are updated accordingly.

* Fixed issue #539 Fixed error opening excel file created in encoding different from UTF-8, added logging of possible errors when decoding XML if the function does not provide exit with an error

* Added test for CharsetReader

* Fixed #discussion_r359397878

Discussion: https://github.com/360EntSecGroup-Skylar/excelize/pull/540#discussion_r359397878

* Fixed go fmt

* go mod tidy and removed unused imports

* The code has been refactored

workBookRelsWriter, drawingRelsWriter into relsWriter;
drawingRelsReader, workbookRelsReader, workSheetRelsReader into relsReader;
addDrawingRelationships, addSheetRelationships into addRels