Fix XSS Vulnerability In "tpl.inc.php"

Another area was also outputting the unsanitized value.
mpdf: Upgrade to 5.7.3
i18n: Package fonts with the Thai language pack

This patch also makes a slight edit to mPDF to allow better detection of
substitions in characters, as the DejaVu fonts shipped do not support Thai
glyphs.
i18n: Proper rtl layout for staff navigation
i18n: rtl: Fix button floating layout for RTL
i18n: rtl: Fix tab display for rtl viewers
i18n: Fix help tip popup for RTL display
i18n: rtl: Fix ticket thread layout
i18n: rtl: Fix dropdowns on action buttons
i18n: rtl: Fixup redactor rtl blocks
i18n: rtl: Fixup filedrop for rtl display
i18n: rtl: Fix quick note layout for rtl display
i18n: pdf: Use Adobe CJK output be default
i18n: rtl: Use linebreaks mode with Redactor and support rtl
Bug: attachments

Auto-detect inline attachments
Attached keepers to canned reply
oops: Properly format text thread bodies
filters: Fixup subfield listing for organizations
oops: Fix bad merge for list properties as sub-fields
forms: If an answer has no saved value, use the field

When processing the value of a DynamicFormEntryAnswer, if there is no
database-backed, value, then use the value of the associated field.
pjax: Fix placement of footer

Footer should not be in #pjax_container, because the footer is not rendered
for non PJAX requests.