Log Message:
Update texmacs to version 2.1.2

Changes:

* Creation of various interface themes for TeXmacs, such as dark
  and bright (2.1.1).
* Improved high resolution support under Linux and Windows (2.1.1).
* Progress on (not yet default) Qt5 version of TeXmacs (2.1.1).
* Updated font database for recent pre-installed Linux/Mac/Window
  fonts (2.1.1).
* Minor bug fixes (2.1).
* Updated plug-in for Giac (1.99.21).
* Better support for the most common LaTeX style files (1.99.20).
* Many corrections for the LaTeX export when using common LaTeX
  styles (1.99.20).
* Added Slovak language support (1.99.20).
* Improved Octave plugin with tab completion and multi-line input
  (1.99.19).
* Enhanced structured search & replace: added preferences and
  wildcards (1.99.19).
* Minor progress on the remote editing tools (1.99.18).
* Improved remote editing tools (1.99.17).
* Lightweight facility for managing user-defined keyboard
  shortcuts (1.99.17).
* Improved customizability of item lists and enumerations
  (1.99.17).
* Further improvements for preview and help balloons (1.99.16).
* Possibility to find labels from their numeric value (1.99.16).
* Incorporation of a smart-ref package for smart references
  (1.99.16).
* Fix spell checking under Windows (1.99.16).
* Rudimentary support for Wacom-style pen tablets, Qt5 only
  (1.99.16).
* Improved help balloons and preview facility for references and
  citations (1.99.15).
* Improved navigation and search tools for labels, references, and
  citations (1.99.15).
* Indicate the current cursor position by shaking the mouse
  (1.99.15).
* Improved Html export with better CSS stylability (1.99.14).
* Improved Octave plugin (1.99.14).