Script to view oracle database reference manual by cui.

This script provide two functions.
First, download online html manual and convert for reading.
Second, can read converted online manual with optional viewer.

Usage
  1) Read this script in the current b-shell environment.(bash or zsh)
      $ source /path/to/oracle-cui-reference.sh

  2) Make converted data with omkdata function.
      $ omkdata { 102 | 111 | 112 | 121 | 122 | all }

     omkdata function requires one argument
     such as release version:

       122 - Oracle Database 12c Release 2 (12.2)
       121 - Oracle Database 12c Release 1 (12.1)
       112 - Oracle Database 11g Release 2 (11.2)
       111 - Oracle Database 11g Release 1 (11.1)
       102 - Oracle Database 10g Release 2 (10.2)
       all - all of the above

     this function relies on wget and w3m.

  3) View converted data using following functions.

       owhat    - What's New / Changes in This Release
       oinit    - Initialization Parameters
       ostat    - Static Data Dictionary Views
       odyn     - Dynamic Performance Views (V$)
       olimits  - Database Limits
       oscripts - SQL Scripts
       owait    - Oracle Wait Events
       oenq     - Oracle Enqueue Names
       ostats   - Statistics Descriptions
       obg      - Background Processes

     these functions recognize two optional arguments.

       o???? [ [ 102 | 111 | 112 | 121 | 122 ] search_word ]

     The first argument specify target release version.
     If this omitted, using ODOC_RELVER variable. (default: 121)

     The second argument used for searching word. This argument
     become effective if $ODOC_VIEWER indicates vi or view or vim.

Options
  The following shell variables affects the execution of functions:

  ODOC_CACHE_DIR
    The location of download file and converted file is stored.
    (default: $HOME/.odoc_cache)

  ODOC_VIEWER
    The name of the viewer program to use for display the manual.
    (default: $PAGER or more)

  ODOC_RELVER
    The number of product version to be used as the default.
    (default: 121)

  ODOC_LANG
    The language of a document to be manipulated.
    Currentry supports "en", "ja".
    (default: ja)

  ODOC_SHRINK
    The level of shrink original documents.
      0: Don't shrink.
      1: Shrink blank lines on a table.
      2: In addition to above, shrink ruled lines on a table.
      3: In addition to above, shrink blank lines on a whole document.

    This variable used by omkdata function only.
    (default: 3)

  ODOC_DYN
    Enables dynamic conversion to display the manual.
    This parameter is useful to view a different terminal width when you convert.
    This parameter is useful when you are using a different terminal width when you convert.
    (default: 0)