Code revision, help messages update

• Small revision, code cleaning
• Help message revision

Adaptive Mode

• Small fixes do help and usage info
• Small update on readme.md

Adaptive mode - Final

• Code cleanup after refactoring
• Fix help info
• Fix readme

Adaptive mode

Now tries different forms of page size detection if the last one fails.
One can force the method of detection with the -m parameter or just use the adaptive mode, which will try each of them by itself.

Methods:

• Cat + Grep
• MacOS mdls
• Linux pdfinfo
• ImageMagick's identify

v1.3.x postscript/ghostscript method was removed until I can write some PS to do that myself.

Better help messages for new stuff

Update help messages for -i mode.

More imagemagick optimization

identify's which binary search was failing silently when not present for no reason.
Just moved a line of code to when we are actually using the imagemagick mode.
Was no real issue (on v1.2.7), just more optimal this way.

ImageMagick as optional + bugfixes

• Added the -i parameter, will use imagemagick for determining the pag size if used
• Fixed an issue on some pdfs that had the /MediaBox or /BBox declaration at the middle or the end of a line

Better page size parsing

Fixed a long-time standing possible problem when parsing the page size. Before, things could go wrong if the MediaBox or BBox did not start with 0 0. Now it is fine, and simpler.

Better paper-size support

Tries to use alternate methods to determine the paper-size.

Fails with error message if paper size is not detected.

MacOS/BSD fix + better parsing

Eliminates the use of expr index since that is not available on MacOS/BSD.
It is actually better for GNU/Linux as well.