Numerous font related fixes (#143, etc).

[skynavga]

• [x] add support for multiple fonts, i.e., font fallback, in tts:fontFamily
• [x] add support for last resort font
• [x] add support for tts:fontSelectionStrategy
• [x] update ttt-fontbox to current pdfbox/fontbox
• [x] enable use of cmap format 13 (required for last resort high efficiency font)
• [x] fix ttml1-prstn-break rendering; ignore tts:display on <br/>
• [x] fix ttml1-prstn-font-size-inherited-em rendering; ensure glyph area font, font size, etc., is used
• [x] add Last Resort, Montserrat, PT Mono, Salsa, Space Mono fonts

Closes #141 Closes #142 Closes #143 Closes #211 Closes #299 Closes #300