solidfiles (probe): fix file size parsing + simplify
core.sh (translate_size): minor, declare => local
core.sh (captcha_process): fix wrong argument to sxiv viewer

Fixes issue 1165.
keep2share: upload works with premium account

Fixes issue 1160.
1fichier: fix account upload

+ premium account download (not tested)
See issue 1162.
filepost: minor, drop duplicated local variable definition
rapidgator: Increase timeout between free downloads

The longer wait time should avoid beeing banned for the
rest of the day.

Also add a debug message for wrong CAPCTHAs.
upstore (download): Fix error checks and add new variant

Note: I have no idea whether this new message replaced the old one
or is used additionally. Lets keep them all for now.
core.sh: rename grep_list_modules() to get_all_modules_list()
turbobit (upload): fix possible wrong return status
tempsend (upload): add sanity check
plowdown, plowup, plowdel: --captchaprogram considers ~/.config/plowshare/exec/ directory

Documentation updated.
Also used (plowdown only) with --run-before and --run-after switches.
filefactory (download): fix images download

Fixes issues 1163.
keep2share (upload): anonymous upload not allowed
keep2share (upload): add basic folder support

New switches:
--folder: name of folder (no hierarchy, will be a root child)
--create: create folder if it does not exist
core.sh: Introduce storage API functions

It can be convenient for modules to save credentials (cookie entry, auth token, session id) to not relogin each time.
Hosters care about that, especially for upload. Too many logins may lead to issues..

With 5 new functions, each module can now save some data in a persistant way.

storage_set KEY STRINGVALUE
VALUE=$(storage_get KEY)
storage_reset
storage_timestamp_set
VALUE=$(storage_timestamp_diff)

File is plain text and is located:
~/.config/plowshare/storage/<module-name>.txt

Each module must be modified accordingly. This is not always possible to cache credentials.

+ bump PLOWSHARE_API_VERSION to 1
plowdown: drop --cookies switch

Module have to implement new storage API in future.
(see revision f3130ecf495d7ab926d49b73d90404a07950c8ce)
core.sh (process_options): add 'c' & 'C' types for argument parsing

c: choice list
C: choice list with empty string allowed. Long options only advised.

declare -r MAIN_OPTIONS="
    LIGHT_MODE,,light,c|on|off|auto=MODE,Set light status
    VERBOSE,v,verbose,c|0|1|2|3|4=LEVEL,Verbosity level: 0=none, 1=err, 2=notice (default), 3=dbg, 4=report
"

'V' argument type (which was made specificaly for verbose switch) is no longer necessary.
core.sh: minor refactor/cleanup

Changes:
- define global $PLOWSHARE_CONFDIR
- deal properly with $TMPDIR
keep2share (upload): first attempt to use storage API