0031756: Data Exchange - broken parsing of STEP entity in case of missing last parameter

0031756: Data Exchange - broken parsing of STEP entity in case of missing last parameter

- Parser is corrected to handle case of missing arguments properly (report error without corruption of the next entity)
- Added counter of entity arguments for appropriate error messages
- Plain C tools and data structures (recfile.*, stepfile.*) are converted to C++ class (StepFile_ReadData) to avoid use of static variables, so that reader can be safely used in a multi-threaded environment