UI cleanup, phase 1 (purely cosmetic)

UI cleanup, phase 1 (purely cosmetic)

One of several commits that are intended to "clean up" parts of
the TomatoUSB GUI.  Expect more in the future (some are hard to
test).  Changes in question:

admin-access.asp
  - Make Authorized Keys textarea more consistent with rest of GUI
  - Grammatical fixups
  - Wrap some text descriptions in parens
  - Better align SSH/Telnet texts, remove unnecessary slash
  - Use smaller font sizes where applicable, and denote units properly
admin-bwm.asp
  - Rename "Link" to "Direct Download Link"
  - Move "Direct Download Link" to right of Backup button
admin-config.asp
  - Rename "Link" to "Direct Download Link"
  - Move "Direct Download Link" to right of Backup button
  - Remove superfluous "Select the configuration file..." text
admin-upgrade.asp
  - Remove unnecessary padding preceding <td> elements
  - Typo: aprox. -> approx.
advanced-firewall.asp
  - Remove unnecessary spaces preceding ICMP/Traceroute fields
  - Clarify what "Enable DSCP Fix" does (reword description)
advanced-misc.asp
  - Capitalisation: Bytes -> bytes
advanced-wlanvifs.asp
  - Add acronymn (VIF) definition to section title
  - Add Notes section sub-headers for each respective area
  - Move <ul> inside LINUX24-BEGIN block; we shouldn't start an
    unordered list if there's no content due to conditionals
  - Make consistent sub-headers and descriptions
  - Remove what appears to be some superfluous HTML
basic-ddns.asp
  - Denote that @IP refers to the WAN IP address
basic-ipv6.asp
  - Remove Notes section; Request PD Only can get its own description
    using a suffix field
  - Remove PPPoE/DSL/Fiber mention; if we aren't sure/don't know, then
    let the user decide.  Don't speculate!
basic-network.asp
  - Use <small> where applicable (i.e. not <i>)
  - Remove parens on things that denote units (ex. minutes, seconds)
  - In Static DNS, IP is supported (not just IP:port)
  - Grammatical fixups
forward-basic-ipv6.asp
  - Change "Proto" to "Protocol" in table; consistent with rest of GUI
  - Fix up Notes section, including spacing and sub-headers
  - Make example syntaxes consistent with rest of GUI
  - Add closing </li> tags
forward-basic.asp
  - Pretty much same as forward-basic-ipv6.asp
forward-triggered.asp
  - Add Notes section designator
  - Add closing </li> tags
forward-upnp.asp
  - Make Miniupnpd Custom Configuration textarea more consistent with
    rest of GUI
  - Make Miniupnpd text actually point to a valid link (example
    miniupnpd.conf file on GitHub); weird that someone left </a>!
  - Remove spurious blank link
tools-ping.asp
  - Remove parens on things that denote units (ex. minutes, seconds)
tools-trace.asp
  - Remove parens on things that denote units (ex. minutes, seconds)