hgweb: add line wrapping switch to file diff and changeset views

hgweb: file diff and changesets views behave like file source view This gives all the benefits introduced before for file source view, namely code selection without line numbers and correct indents, highlighting line which is linked to, long lines wrapping. Implementation strategy is also the same as for file source view: all the lines are put in a sigle pre tag with span's for each line. Correct line numbering (same as before this patch) is achieved with nested CSS counters.

hgweb: introduce separate classes for stripey background Introduce stripes2 and stripes4 classes to support different structure. They will be useful to implement stripes with pure CSS everywhere instead of current server-side implementation.

hgweb: add line wrapping switch to file source view This uses classList property, which is well-supported now: both Chromium 8.0+, Firefox 3.6+ and Opera 11.5+ support it, as well as relatively modern versions of other browsers.

hgweb: add changelog and search templates to raw style This will make testing hgweb search and other things simpler and more concise, as there is no extra HTML code in the raw style.

hgweb: toggleDiffstat function instead of showDiffstat and hideDiffstat This eliminates the need of two almost equal functions, makes the code cleaner.

doc: make i18n man and html Allow overwrite LANGUAGE and LC_ALL make variables, for make i18n man and html. After this patch, we can make i18n man and html by following command: $ make clean all LANGUAGE=ja