readdlm improvements:

- speed up reading of large files if dimensions are known
- prefer doing two passes when offset storage may take too much ram
- moved readdlm into a module to contain symbols
Document symbol punctuation
Merge pull request #6720 from rsrock/patch-1

Document symbol punctuation
Allow `test_throws` to take an user-defined exception type
Merge pull request #6727 from kshramt/kshramt/fix_test_throws

Allow `test_throws` to take an user-defined exception type
fix minor typo in C calling docs
Merge pull request #6729 from porterjamesj/patch-1

fix minor typo in C calling docs
allow tests to be run without a network
R: Explained differences of max, maximum , sum, etc.

See #6724
changed colletion to collection
Merge pull request #6732 from mkriele/master

R: Explained differences of max, maximum , sum, etc.
Merge pull request #6730 from amitmurthy/amitm/nonet

allow tests to be run without a network
Add section on working with files to Streams docs
Merge pull request #6738 from porterjamesj/patch-1

Add section on working with files to Streams docs
Simplify jl_raise_debugger, fix #6723
cleanup in runtests.jl
Merge pull request #6745 from amitmurthy/amitm/nonetfix

cleanup in runtests.jl
Merge pull request #6718 from tanmaykm/readcsv

readdlm improvements for reading large files