* Add render package
* Add text state
* Add more text operators
* Remove unnecessary files
* Add text font
* Add custom text render method
* Improve text rendering method
* Rename text state methods
* Refactor and document context interface
* Refact text begin/end operators
* Fix graphics state transformations
* Keep original font when doing font substitution
* Take page cropbox into account
* Revert to substitution font if original font measurement is 0
* Add font substitution package
* Implement addition transform.Point methods
* Use transform.Point in the image context package
* Remove unneeded functionality from the render image package
* Fix golint notices in the image rendering package
* Fix go vet notices in the render package
* Fix golint notices in the top-level render package
* Improve render context package documentation
* Document context text state struct.
* Document context text font struct.
* Minor logging improvements
* Add license disclaimer to the render package files
* Avoid using package aliases where possible
* Change style of section comments
* Adapt render package import style to follow the developer guide
* Improve documentation for the internal matrix implementation
* Update render package dependency versions
* Apply crop box post render
* Account for offseted media boxes
* Improve metrics of rendered characters
* Fix text matrix translation
* Change priority of fonts used for measuring rendered characters
* Skip invalid m and l operators on image rendering
* Small fix for v operator
* Fix rendered characters spacing issues
* Refactor naming of internal render packages
* Added text bounding box extraction.
* Add `font` field to textMark struct;
Create a new method `TextComponents` to retrieve all the text components of the extracted text in the page, with position and character informations
* Reorganizing extractor/text.go
* Added a text extraction position test.
* Added another text extraction location test.
* Text extraction location testing.
* Added tests for text extraction with location information.
* Cleaned up text extraction tests. No changes to functionality.
* Simplifying text extraction code.
* Simplified line construction in text.go
* Returning TextMark's in TextMarkArray which are based on PdfObjectArray but read-only, so not pointers.
* Added text extraction to show PDFs marked-up with bounding boxes of substring in extracted text.
* Add comments explaining how to calculate text bounding boxes.
* Made text_test.go naming consistent with function comments in text.go
* Use tm, pt, tl for textMark/TextMark PageText and TextLine receivers and local variables.
* uncommeted text stress test. Use go test --short to skip
* TextMark.Offset is now an index into the extracted text. It was an index into []rune(text)
