core.sh (match_remote_url, basename_url): URL schemes are case-insensitive

According to RFC3986 (section 3.1):
"An implementation should accept uppercase letters as equivalent to lowercase
in scheme names (e.g., allow "HTTP" as well as "http") for the sake of
robustness but should only produce lowercase scheme names for consistency."

Enhancement of match_remote_url:
You can add additional arguments to the function to accept extra schemes.

For examples:
match_remote_url "$STRING" <= matches http, https
match_remote_url "$STRING" 'ftp' <= matches http, https, ftp
match_remote_url "$STRING" 'ftp' 'file' <= matches http, https, ftp, file
core.sh (prompt_for_password): add 1 hour timeout for read
core.sh: use "read -r"

-r switch means: backslash does not act as an escape character.

We surely always want raw mode..
man page (plowshare.conf.5): tiny update (clarify double quote usage)
plowprobe: tiny log_debug fix

This is a completion of commit
plowprobe: add log_debug when link is retricted (password, premium)
revision 4bc766dc02d8e3099f35a283ff55f6436d53337c
bayimg: add module with anonymous upload & download

Fixes issue 961.
zalaa (upload): avoid pipe, fix error 141 (SIGPIPE)

Fixes issue 971.
core.sh (match_remote_url): doc fix

See revision 5992f27014b0b2269161a850528e16ff67c6c1ed for initial commit.
core.sh: doc, clarify $ERR_LINK_PASSWORD_REQUIRED
man page (plowdel.1): add missing exit code ($ERR_LINK_PASSWORD_REQUIRED)
bayimg (upload): add --admin-code module switch

Like in uploaded.net
1fichier (download): minor, move test block
plowdown: raw IPv4 sanity check (use bash regexp)
netload.in (premium download): minor, avoid pipe
core.sh: introduce grep_http_header_content_length API

Same behavior as other grep_http_header_* functions.
filebin.ca: new module with anonymous download and upload

Download links are direct!
Fixes issue 982.
shareonline_biz (download): add premium support

Note: Premium compatibility of upload function was also checked.
billionuploads: fix, upstream modified

Fixes issue 993.
plowprobe: tiny log_notice fix

This is a completion of commits:
revision 37dc0d0af8ee766d0b2a5a7118b2ea5b03e3dedf
revision 4bc766dc02d8e3099f35a283ff55f6436d53337c
anonfiles (download): fix, upstream modified

+ add probe support