Added {.cpp} highlighting markers to the C++ code blocks in documentation;
Excessive tildes "~~~~~~~" in code block borders are reduced to required minimum of "~~~~" (4);
Removed obsolete space bars after code block borders;
TCL code blocks are now highlighted with {.php} markers;
Removed excessive {.cpp} highlighting markers appended to non-code blocks such as lists, reports and file content or structure examples;
Minor fixes for tests.md and draw_test_harness.md (whitespace removal and structural fix for "Where:" in code examples);
Minimum HDD space for OCCT updated in introduction.md.
Revision of Introduction, Overview, Samples, Tutorial
- Technical Overview is incorporated into Introduction
- Samples (from Overview) and Tutorial are moved into new section Tutorials and Samples
- Content of Getting Started section (Draw Test Harness and Experimenting with Draw Test Harness) is moved into Tutorial and Samples section.
- Content changes: links to Open Cascade website promoting paid training and support are deleted.
- Some pictures in User Guides (Foundation Classes, Modeling Data, Modeling Algorithms) and Tutorial are updated to improve quality and correct mistakes.
