closes#917
Summary follows:
- src/menu/menu.c: add `leave` action to call lab-exit.
- clients/meson.build: add install routine for lab-exit
and lab-sensible-terminal.
- meson.build remove lab-sensible-terminal routine re the comment.
- po/labwc.pot: rebuild with new xgettext commands.
- po/it.po: add translations for lab-exit and edit my email.
- CONTRIBUTING.md#translations: modify the instructions for coders as
two xgettext commands are needed since we now have two GUI facing
languages that have translatable strings.
- style "GLib" with two capitals as in its own upstream docs
- use title-case consistently for headings
- add missing heading to table of contents
- update dead GLib documentation URL
- typos: LINGUAS manually, rest with help of aspell(1)
- whitespace: some trailing spaces/tabs, one utf-8 NBSP (#xC2 #xA0)
- made most text in docs/ fit in max 80-column wide lines
- consistent trailing periods in sentences in labwc-actions.5.scd and
labwc-config.5.scd; labwc-theme.5.scd had different consistency,
changed it follow these other files with sentence-ending periods
- and ", respectively" (comma often used to separate)
- Clarify the coding style relative to Linux kernel and Devault rules
- Add g_pattern_match_simple() example
- Add namespace advice and preference
- Elaborate on preferred header documentation style.
- Add table of contents
- Simplify API section and add wl_list_append()
- adds labwc.pot and po files for de, es, it and sv
- added notes in NEWS.md and CONTRIBUTING.md
- addresses #269
- conditional upon `msgfmt` being installed
- can be disabled at build time
