move loading of sparse data into SGSparseMatrix

- drop load_from_svmlight file from SparseFeatures
- return an SGVector<float64_t> when loading with labels
use tmpname and unlink in mldata unit test
Added gdb checker
Proper gdb path in gdb checker
replace binary comparison with our new equals method
fixed a very tricky bug which caused memory errors when calling
TParameter::equals on CT_VECTOR or CT_MATRIX with ST_STRING of
primitive type not equal to PT_CHAR, i.e. PT_FLOAT64.

This also fixed some integration test equaks failures since we have
cases of vectors if string, as for example in string features

Note to myelf: DON'T DEVELOP USING COPY/PASTE
Revert "Disabled integration tests on travis"

This reverts commit 1564b47cc11cc5c1a3c6a9de6a8027a0522dcc23.
added comment about new equals in integration tester.py
handle tolerance=None and put a default value of 1e-5 since more accuracy seems to be tricky with ascii
Merge pull request #1652 from karlnapf/develop

replace binary comparison with our new equals method
use python to detect date of NEWS file

this is more cross-platform
adjust for API changes: use new load_with_labels functions
minor changes in log-det
Temporarily disabled gdb checker to avoid hanging buildbots
Merge pull request #1656 from lambday/feature/log_determinant

minor changes in log-det
Change to be able to use BoolVector correctly in python modular
Merge pull request #1653 from van51/feature/bool_modular

Change to be able to use BoolVector correctly in python modular