Fix/ole emf header alternative

[OssianEPPlus]

Before submitting this pull request I have...

• [X] read EPPlus Softwares Contribution Guidlines
• [X] ensured that the functionality I have added/changed is covered by new unit tests.
• [X] merged the target branch into the PR branch and resolved any merge conflicts
• [X] Run all the unit tests and ensured that they all are green (unless the purpose of the PR is to provide us with failing unit tests).

Added alternate headers and font handling. Also added correct character spacing for emf files based on fonts