COR-329 : New implementation of the MSExcelDocumentReader using the Even...

New implementation of the **MSExcelDocumentReader** using the **Event User Model** approach to have ** lower memory footprint with big Excel files**.

The new Reader follow the following rules : 

we only index :
* a maximum of 5000 cells starting from the first tab
* after 5000 cells processed, we abort the parsing

we KEEP only the following data :
* tab name
* cells with string with a length > 2 chars

we SKIP the following data :
* cells with string with a length < 3 chars
* cells with number (date formatted or simple number)
* cells with blank value
* cells with boolean or error value
* cells with formula

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New implementation of the **MSXExcelDocumentReader** using the **Event User Model** approach to have **lower memory footprint with big Excel files**.

The new Reader follow the following rules : 

we only index :
* a maximum of 5000 cells starting from the first tab
* a maximum of 5 tabs
* a maximum of 1000 cells processed per tab

we KEEP only the following data :
* tab name
* cells with string with a length > 2 chars

we SKIP the following data :
* cells with string with a length < 3 chars
* cells with number (date formatted or simple number)
* cells with blank value
* cells with boolean or error value
* cells with formula

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New implementation of the **POIPropertiesReader.readDCProperties(...)** for ooxml documents (MS 2007 office file formats) to have **lower memory footprint with big Excel (xlsx) or Word (docx) or Power Point (pptx) files**.