Rename variables for best practices.

This requires renaming the variables in one's ~/.freenetrc.

It is good practice to use variable names with at least one lowercase
letter to avoid overriding environment or internal shell variables
which are in all caps. See #bash greybot's !varcaps factoid.

For configuration consistently use "dir" for directories and "path" for
file locations. Braces around a variable are needed only in cases of
ambiguity.

${OLDVER}-${NEWVER}.diff.txt -> $diffName

DRY_RUN -> dryRun
TARGET -> target
WINEDEBUG -> wineDebug
START_STOP_SSH_AGENT -> useSshAgent

BUILD_DIR -> buildDir
RELEASE_DIRECTORY -> releaseDir
SWITCHTEMP -> signDir
TEMPLOC -> buildDir
WININSTALLER_PATH -> wininstallerDir
WORKSPACE_FRED -> fredDir

CONFIG -> configPath
FREENET_EXT_JAR -> freenetExtPath

JAR_FILENAME -> jarName
ARCHIVE_FILENAME -> archiveName

SIGNING_USER -> signingUser
WINE_USER -> wineUser

TARGET_HOST -> targetHost
NODE_FCP_HOST -> fcpHost
NODE_FCP_PORT -> fcpPort

NEWVER -> newBuild
OLDVER -> oldBuild
GITVERSION -> gitVersion
VER -> build
VERSION -> buildNumber
Remove reference to outdated browser user.
Clean up upload status output.

No need to reference VM name as it's configurable. Webserver is what it
means conceptually.
Merge branch 'master' of github.com:freenet/scripts
Update deploy-website to use ~/.freenetrc.

Removes the repo location command line switches, adds one for --config,
and adds websiteStagingDir and websiteOfficialDir to freenetrc.
Use heredocs for --help.

Avoids repeated use of echo.
Remove unnecessary operations in clean checkout.

No need to set the local master to the remote one.
Allow relative wininstallerDir.
Move shared functions and default config to common.

Generating l10n changeset, getting git version and build number, and
reading configuration are common functions.

buildTag -> gitVersion
buildVersion -> buildNumber