Get information about template slides and shapes

• Merge pull request #61 from MP70/getAllTextElements 8e5fe18
• fix(xml): use creationIds; check for existing text content; 67506e0
• prettier cdd7a83
• tidy and comment e80f2f3
• test template 915ebb7
• add getTextEleIds a567f07
• test 6007b84
• chore: add some interfaces to export 833e0d6
• Merge pull request #59 8ac8621
• tests 2fb22af
• Add slide number helper and pass thru to template d071faf
• chore(master): extend type map to support e.g. think-cell relations on layouts 3001ca8

v0.3.3...v0.3.4