SVGHMI: update generated XSLT

Merged

SVGHMI: make a copy of tests/svghmi as test/svghmi_widget because too crowded since having pages for widget documentation. Strip those pages from tests/svghmi, so that it
is more light for regular testing.

SVGHMI: Prevent excluded widget to appear in generated pages' widget list.

SVGHMI: Remove recursive walk in parsed widget to find unique type and use xsl:key instead.

SVGHMI: Fix browser side exception when some widget are not used, and are then discarded and not present in final SVG. In that case JS code was still making reference to discarded widget elements and was raising exception at init.

SVGHMI : removed support for changing keyboard position and showing at user defined location. Feature was problematic in many respect.

SVGHMI: Make an error when pages are nested

SVGHMI: i18n: finished passing back translated messaged to xslt proc, finished template to generate corresponding javascript literals.

SVGHMI: i18n: various fixes about unicode encoding and converting translation result back to XML to feed xslt processor

SVGHMI: i18n: better warning messages, more explicit.

SVGHMI: i18n: now loads PO filesand match translation against catalog. Refactored a bit to move i18n related code in i18n.py

SVGHMI: still WIP, now POT file is properly generated with utf-8 encoding and POEdit is launched when pressing button.

Docutil : reworked Inkscape launching and path resolution in docsvg.py

merge

Removed harmful assert in ProcessLogger.

ProcessLogger was having an assert in constructor when missing logger, leading to systematic exception when testing options accepted by compiler. This exception was silenced in ProjectController, and then MatIEC was always called without options.