Nibetaseries

* [ENH] add nthreads option and make multiproc the default (81) jdkent
* [FIX] add missing comma in hrf_models (83) jdkent

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Adding one feature that will make my thesis work easier,
outputting the residual timeseries after beta series estimation.
This release also contains changes to update links to the "new"
default travis ci .com and makes sure I'm using sphinx 2.x.x,
and not the new 3.x.x.

* [ENH] add --return-residuals (304) jdkent
* [MAINT] update travis badge and pin sphinx (305) jdkent

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This release adds two EXPERIMENTAL flags:
--normalize-betas and --no-signal-scaling.
I'm especially unsure about the behavior of
--normalize-betas in combination with any hrf that contains
"derivatives" or "derivatives + dispersion", since I'm unsure
when to divide the the beta estimates with the variances of
the beta estimates to derive the t-statistic
(i.e., normalizing the beta estimates).
This release also has given access to residuals from the LSA and LSS
interfaces.

Another WARNING: residuals for the LSS interface are not quite as meaningful
since I'm averaging the residuals over all the models being generated.
This project is not version 1.x.x yet, so be aware aspects of the API
may change rapidly.

Thanks to michaelmack for opening an issue to suggest new features and
PeerHerholz for their contributions!

* [ENH] add --normalize-betas option (299) jdkent
* [ENH] add --no-signal-scaling option (298) jdkent
* [ENH,FIX] optimally combine temporal + dispersion derivatives for beta estimation (296) jdkent
* [ENH] add residuals to LSS/LSA interfaces (294) jdkent
* [FIX] remove standardize parameter (292) jdkent
* [ENH] Allow niftiimage input (289) jdkent
* fix singularity install instructions in docs (288) PeerHerholz

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Bug fix and enhancement release.
Made a quick decision to remove volumes that have large unstable beta estimates.

* [FIX] allow atlas arguments to be None (283) jdkent
* [FIX] bump nipype version (280) jdkent
* [ENH] censor invalid volumes (277) jdkent
* [ENH] allow regex for confound specification and impute derivatives (273) jdkent

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Bug fix and maintenance release.

* [DOC] emphasize beta map analysis (270) jdkent
* [FIX] allow other spaces (269) jdkent
* [FIX] less strict beta map generation (262) jdkent
* [ENH] handle all confound NaNs (255) jdkent
* [ENH] improve bids indexing (253) jdkent
* [FIX] allow "sub-" prefix (256) jdkent

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Bug fix and maintenance release.

* [MAINT] refactor and increase tests for run.py (249) jdkent
* [FIX] allow flexible derivatives location (247) jdkent
* [ENH] create useful error message when images are not found (246) jdkent
* [MAINT] fix nistats dependency (245) jdkent