  Understanding the formation of stellar clusters requires following the
interplay between gas and newly formed stars accurately. We therefore couple
the magnetohydrodynamics code FLASH to the N-body code ph4 and the stellar
evolution code SeBa using the Astrophysical Multipurpose Software Environment
(AMUSE) to model stellar dynamics, evolution, and collisional N-body dynamics
and the formation of binary and higher-order multiple systems, while
implementing stellar feedback in the form of radiation, stellar winds and
supernovae in FLASH. We here describe the algorithms used for each of these
processes. We denote this integrated package Torch. We then use this novel
numerical method to simulate the formation and early evolution of several
examples of open clusters of ~1000 stars formed from clouds with a mass range
of 10^3-10^5 M_sun. Analyzing the effects of stellar feedback on the gas and
stars of the natal clusters, we find that in these examples, the stellar
clusters are resilient to disruption, even in the presence of intense feedback.
This can even slightly increase the amount of dense, Jeans unstable gas by
sweeping up shells; thus, a stellar wind strong enough to trap its own H II
region shows modest triggering of star formation. Our clusters are born
moderately mass segregated, an effect enhanced by feedback, and retained after
the ejection of their natal gas, in agreement with observations.
