debian: replace rmodifier by trigger in control file
trigger: update description of trigger plugin
Use asciidoc file ending for all asciidoc files
core: add "foreign" for AM_INIT_AUTOMAKE to ignore missing files and remove some warnings
core: add .asciidoc files in main Makefile.am
core: add link to formatted version of {ChangeLog|NEWS}.asciidoc
relay: add signals "relay_client_xxx" for client status changes (closes #2)

New signals:
- relay_client_connecting
- relay_client_waiting_auth
- relay_client_connected
- relay_client_auth_failed
- relay_client_disconnected
relay: add info "relay_client_count" with optional status name as argument

Use in evaluated strings (for example in /eval or triggers):
- "${info:relay_client_count}": total number of relay clients (any status)

With a specific status:
- "${info:relay_client_count,connecting}"
- "${info:relay_client_count,waiting_auth}"
- "${info:relay_client_count,connected}"
- "${info:relay_client_count,auth_failed}"
- "${info:relay_client_count,disconnected}"
core: rename file NEWS.asciidoc to ReleaseNotes.asciidoc
core: move content of INSTALL.asciidoc into README.asciidoc
core: add file Contributing.asciidoc
core: fix typo in Contributing.asciidoc
core: add sub-sections and note about scripts in Contributing.asciidoc
core: add asciidoc attribute "lang" in Contributing and README
core: add a WeeChat screenshot in README.asciidoc
core: fix recursive calls to function eval_expression
core: add option weechat.look.hotlist_add_conditions, remove option weechat.look.hotlist_add_buffer_if_away
de.po: add missing translations
relay: fix crash on /upgrade received from a client (weechat protocol)

Some commands like /upgrade sent by relay client can cause problems, because
they were executed immediately (while relay code is running). The /upgrade
command unloads all plugins, so the result is unpredictable (it can cause a
crash).

This commit adds a timer (1 millisecond) to delay the execution of command
after we go back in the WeeChat main loop.
doc: update German auto-generated files