For some reason it seems that my favourite editor TeXnicCenter doesn't support unicode (correct me please if I'm wrong, which wouldn't be the first time).
Can anyone recommend an editor which does, for Windows platform? Simplicity is appreciated.
[Tex/LaTex] Editors supporting unicode
editorsunicode
Related Solutions
The problem is with tex4ht, application which converts dvi file to html, doesn't support opentype fonts and compilation fails when one is used. Because it seems there is nobody who understand tex4ht c source and would be able to fix this bug, the only solution is to hack unicode-math to not use opentype fonts with tex4ht.
I hacked fontspec in similar way and it worked with texlive 2012, I am not sure about texlive 2013, since there was upgrade of many involved packages - package code and info page. I tried also to hack unicode-math, but I failed with that.
You can add some support with \DeclareUnicodeCharacter, but it would fail in some cases, as you noted.
Edit For your edited question, I can correctly compile your example, if I edit it little bit:
\documentclass{article}
\ifdefined\HCode
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{newunicodechar}
\newunicodechar{ö}{\"o}
\newunicodechar{φ}{\phi}
\else
\usepackage{unicode-math}
\setmathfont{Asana-Math.otf}
\fi
\begin{document}
Löse $\sqrt{φ} = 1$
\end{document}
and compile with
htxelatex filename "xhtml, mathml, charset=utf-8" " -cunihtf -utf8"
A simple example using ucharclasses package:
\documentclass{article}
\usepackage{ucharclasses}
\usepackage{fontspec}
\usepackage{bidi}
% some fonts with Windows
\setDefaultTransitions{\fontspec{Times New Roman}}{}
\setTransitionsForCJK{\fontspec{SimSun}}{}
\setTransitionsForArabics{\fontspec{Times New Roman}\setRTL}{\setLTR}
\setTransitionsFor{Gurmukhi}{\fontspec{Raavi}}{}
\begin{document}
\begin{tabular}{ll}
Arabic (MSA) & حَوّامتي مُمْتِلئة بِأَنْقَلَيْسون \\
Chinese (Mandarin, Simplified) & 我的气垫船充满了鳝鱼 \\
Punjabi & ਮੇਰਾ ਹਵਰਕ੍ਰਾਫ਼ਤ ਨਾਂਗਾਂ ਨਾਲ਼ ਭਰਿਆ ਪਿਆ।\\
\end{tabular}
\end{document}
You should read the package document and set the proper fonts.
The use of loop in your question is OK. See also my previous answer in Generating a table of glyphs with XeTeX , but \iffontchar is not necessary.
Best Answer
According to the TeXnicCenter site, there'a an alpha version that supports unicode: TeXnicCenter 2.0 Alpha 1.
If you are willing to change your editor, perhaps the answers to this question can be useful for you: LaTeX Editors/IDEs.
I personally use TeXworks (I use it under Linux, but it is multiplataform, so you can also use it on Windows machines).